User equipment-centric inter-cell mobility

ABSTRACT

An indication signal is used for indicating to a UE a communication resource for a second reference signal that is part of a higher-layer configuration from a first base station. The communication resource for the second reference signal is associated with a second base station. The higher-layer configuration also includes a communication resource for a first reference signal associated with the first base station. A UE that receives an indication signal communicates with the second base station. A data transmission or a control signal transmission could be communicated with the second base station using a respective data channel or control channel. The data channel or control channel is associated with the communication resource for the second reference signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/827,923, filed on Mar. 24, 2020 and entitled “USEREQUIPMENT-CENTRIC INTER-CELL MOBILITY”, which claims the benefit of U.S.Provisional Application No. 62/826,230, filed on Mar. 29, 2019 andentitled “USER EQUIPMENT-CENTRIC INTER-CELL MOBILITY”, the entirecontents of both of which are incorporated herein by reference.

FIELD

The present disclosure relates generally to wireless communications and,in particular, to User Equipment mobility between different cells in awireless communication network.

BACKGROUND

In traditional cellular networks, each transmit/receive point (TRP) isassociated with a coverage area or a traditional TRP-based cell and isassigned a traditional cell identifier (cell ID) to define a controlchannel and a data channel so that simultaneous TRP to UE or UE to TRPcommunications can be supported for each traditional cell. The networkmay maintain the association between a serving TRP and a UE through theassigned traditional cell ID until a handover is triggered.

As the demand on mobile broadband increases, traditional cellularnetworks are deployed more densely and heterogeneously with a greaternumber of TRPs. Traditional cell ID assignment becomes more difficultand the occurrence rate of handovers increases as the UE moves betweenTRPs.

Current solutions deployed in cellular networks such as Long TermEvolution (LTE) and New Radio (NR) Release 15 address two types of UEmobility, including mobility within cells and mobility between cells.Intra-cell mobility within cells involves management of cell-specificcommunication resources and cell-specific configurations. Antenna beamsrepresent an example of such communication resources, and so-called beammanagement could be used in some network implementations for intra-cellmobility within one cell. Inter-cell mobility between cells is alsoreferred to as mobility management.

Beam management was introduced in NR for the purpose of handlingmobility within a given cell. This involves procedures used such as BeamFailure Detection (BFD) and Beam Failure Recovery (BFR). In mobilitymanagement, however, a UE experiences mobility interruption time duringwhich there is an interruption in communications, because a UE firstreleases its link with a source cell and then establishes a new linkwith a target cell. Mobility management involves higher-layer signalingexchange between the UE and network equipment.

SUMMARY

Aspects of the present disclosure relate to avoiding interruption in UEcommunications when a UE is moving from one cell to another, for exampleby enabling the problem of mobility between cells to be treatedsimilarly to the problem of mobility within cells. Inter-cell mobilitymanagement could then be an extension of intra-cell mobility management,without introducing interruptions in connectivity and communications asa UE is moving between cells. A beam switching command, for example,could be sent to and executed by a UE without interrupting connectivityand communications.

A method according to an aspect of the present disclosure involvesreceiving, by a UE from a first base station, an indication signal. Theindication signal is for indicating to the UE a communication resourcefor a second reference signal associated with a second base station. Thecommunication resource for the second reference signal is comprised in ahigher-layer configuration from the first base station to the UE, andthe higher-layer configuration further comprises a communicationresource for a first reference signal associated with the first basestation. A method may also involve communicating, by the UE with thesecond base station, a data transmission or a control signaltransmission using a respective data channel or control channel. Thedata channel or control channel is associated with the communicationresource for the second reference signal.

Another method involves generating, by a first base station, anindication signal for indicating to a UE a communication resource for asecond reference signal associated with a second base station. Thecommunication resource for the second reference signal is comprised in ahigher-layer configuration from the first base station to the UE, andthe higher-layer configuration further comprises a communicationresource for a first reference signal associated with the first basestation. A method may also involve transmitting the indication signalfrom the first base station to the UE. The indication signal istransmitted to the UE to enable the UE to communicate, with the secondbase station, a data transmission or a control signal transmission usinga respective data channel or control channel. The data channel orcontrol channel is associated with the communication resource for thesecond reference signal.

According to another aspect of the present disclosure, a UE includes aprocessor and a non-transitory computer readable storage medium storingprogramming for execution by the processor. The programming includesinstructions to receive, from a first base station, an indicationsignal. The indication signal is for indicating to the UE acommunication resource for a second reference signal associated with asecond base station. The communication resource for the second referencesignal is comprised in a higher-layer configuration from the first basestation to the UE, and the higher-layer configuration further comprisesa communication resource for a first reference signal associated withthe first base station. The programming also includes instructions tocommunicate, with the second base station, a data transmission or acontrol signal transmission using a respective data channel or controlchannel. The data channel or control channel associated with thecommunication resource for the second reference signal.

A base station may include a processor and a non-transitory computerreadable storage medium storing programming for execution by theprocessor. The programming includes instructions to generate, by thebase station, an indication signal for indicating to a UE acommunication resource for a second reference signal associated with asecond base station. As noted above, the communication resource for thesecond reference signal is comprised in a higher-layer configurationfrom the base station to the UE, and the higher-layer configurationfurther comprises a communication resource for a first reference signalassociated with the base station. The programming also includesinstructions to transmit the indication signal from the base station tothe UE, to enable the UE to communicate, with the second base station, adata transmission or a control signal transmission using a respectivedata channel or control channel associated with the communicationresource for the second reference signal.

Other aspects of the present disclosure relate to a computer programproduct comprising a non-transitory computer readable storage mediumstoring programming, and to such a non-transitory computer readablestorage medium storing programming. For example, the programming mayinclude instructions to perform a method as disclosed herein. In anembodiment, the programming includes instructions to receive, from afirst base station, an indication signal for indicating a communicationresource for a second reference signal associated with a second basestation. The communication resource for the second reference signal iscomprised in a higher-layer configuration from the first base station,and the higher-layer configuration further comprises a communicationresource for a first reference signal associated with the first basestation. The programming may also include instructions to communicate,with the second base station, a data transmission or a control signaltransmission using a respective data channel or control channel. Thedata channel or control channel is associated with the communicationresource for the second reference signal.

As another example, the programming may include instructions togenerate, by a base station, an indication signal for indicating to a UEa communication resource for a second reference signal associated with asecond base station. The communication resource for the second referencesignal is comprised in a higher-layer configuration from the basestation to the UE, and the higher-layer configuration further comprisesa communication resource for a first reference signal associated withthe base station. The programming may also include instructions totransmit the indication signal from the base station to the UE. Theindication signal is transmitted to the UE to enable the UE tocommunicate, with the second base station, a data transmission or acontrol signal transmission using a respective data channel or controlchannel. The data channel or control channel is associated with thecommunication resource for the second reference signal.

According to a further aspect of the present disclosure, a methodinvolves a UE receiving an indication signal from a first base station.The indication signal is for indicating to the UE a communicationresource of a second reference signal from a higher-layer configurationfrom the first base station. The higher-layer configuration includes notonly a communication resource for a first reference signal associatedwith the first base station, but also the communication resource for thesecond reference signal associated with a second base station. Such amethod could also involve the UE communicating with the second basestation. A data transmission or a control signal transmission could becommunicated with the second base station using a respective datachannel or control channel. The data channel or control channel isassociated with the communication resource of the second referencesignal.

Another method involves generating, by a first base station, anindication signal and transmitting the indication signal from the firstbase station to a UE. As described above and elsewhere herein, theindication signal is for indicating to the UE a communication resourceof a second reference signal from a higher-layer configuration from thefirst base station, and the higher-layer configuration includes acommunication resource for a first reference signal associated with thefirst base station and the communication resource for the secondreference signal associated with a second base station. The indicationsignal is transmitted from the first base station to the UE to enablethe UE to communicate with the second base station, a data transmissionor a control signal transmission using a respective data channel orcontrol channel. The data channel or control channel is associated withthe communication resource of the second reference signal.

A UE could include a processor and a non-transitory computer readablestorage medium storing programming for execution by the processor. In anembodiment, the programming includes instructions to receive, by the UEfrom a first base station, an indication signal for indicating to the UEa communication resource of a second reference signal from ahigher-layer configuration from the first base station, and tocommunicate, by the UE with the second base station. The higher-layerconfiguration includes both a communication resource for a firstreference signal associated with the first base station and thecommunication resource for the second reference signal associated with asecond base station. The UE could communicate, with the second basestation, a data transmission or a control signal transmission using arespective data channel or control channel. The data channel or controlchannel is associated with the communication resource of the secondreference signal.

The present disclosure also relates in part to a base station, which inan embodiment includes a processor and a non-transitory computerreadable storage medium storing programming for execution by theprocessor, with the programming including instructions to generate, bythe base station, an indication signal for indicating to a userequipment (UE) a communication resource of a second reference signalfrom a higher-layer configuration from the base station to the UE, andto transmit the indication signal from the base station to the UE. As inother embodiments referenced above and elsewhere herein, thehigher-layer configuration includes a communication resource for a firstreference signal associated with the base station and the communicationresource for the second reference signal associated with a second basestation. The base station transmits the indication signal to the UE toenable the UE to communicate with the second base station, a datatransmission or a control signal transmission using a respective datachannel or control channel associated with the communication resource ofthe second reference signal.

Embodiments could also or instead be implemented in other ways. Forexample, a computer program product could include a non-transitorycomputer readable storage medium storing programming, with theprogramming including instructions to perform a method as disclosedherein.

In a computer program product including a non-transitory computerreadable storage medium storing programming, the programming couldinclude instructions to receive, by a UE from a first base station, anindication signal, and to communicate, by the UE, with a second basestation. The indication signal is for indicating to the UE acommunication resource of a second reference signal from a higher-layerconfiguration from the first base station, and the higher-layerconfiguration includes both a communication resource for a firstreference signal associated with the first base station and thecommunication resource for the second reference signal associated withthe second base station. UE communications with the second base stationcould include, a data transmission or a control signal transmissionusing a respective data channel or control channel associated with thecommunication resource of the second reference signal.

Another example of a computer program product includes a non-transitorycomputer readable storage medium storing programming, and theprogramming includes instructions to generate, by a first base station,an indication signal for indicating to a UE a communication resource ofa second reference signal from a higher-layer configuration from thefirst base station to the UE, and to transmit the indication signal fromthe first base station to the UE. The higher-layer configurationincludes both a communication resource for a first reference signalassociated with the first base station and the communication resourcefor the second reference signal associated with a second base station.Transmission of the indication to the UE is to enable the UE tocommunicate with the second base station, a data transmission or acontrol signal transmission using a respective data channel or controlchannel associated with the communication resource of the secondreference signal.

Other aspects and features of embodiments of the present disclosure willbecome apparent to those ordinarily skilled in the art upon review ofthe following description.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present embodiments, and theadvantages thereof, reference is now made, by way of example, to thefollowing descriptions taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates an example communication system in which embodimentsof the present disclosure could be implemented;

FIG. 2 illustrates two neighboring NR cells of an example communicationsystem in which embodiments of the present disclosure could beimplemented;

FIG. 3 is a flow diagram illustrating a method according to anembodiment;

FIG. 4 is a flow diagram illustrating a method according to anotherembodiment;

FIG. 5 is a block diagram illustrating coverage areas or cells in awireless communication network;

FIG. 6 is a block diagram illustrating two adjacent coverage areas orcells in a wireless communication network;

FIG. 7 is a signaling diagram illustrating inter-cell mobility signalingaccording to an embodiment;

FIG. 8 is a signaling diagram illustrating an example of higher-layerconfiguration signaling and inter-cell mobility signaling in accordancewith some embodiments;

FIG. 9 is a signaling diagram illustrating another example ofhigher-layer configuration signaling and inter-cell mobility signaling;

FIG. 10 is a block diagram illustrating an example serving cellconfiguration stored at a UE;

FIG. 11 is a flow diagram illustrating a method according to anotherembodiment;

FIG. 12 is a flow diagram illustrating a method according to a furtherembodiment;

FIG. 13 is a block diagram illustrating features that could beimplemented in a communication system at a UE and network equipment;

FIGS. 14 and 15 illustrate example devices that may implement themethods and teachings according to this disclosure.

DETAILED DESCRIPTION

As noted above, as the demand on mobile broadband increases, traditionalcellular networks are deployed more densely and heterogeneously with agreater number of TRPs, and the occurrence rate of handovers as the UEmoves between TRPs increases. This could be an issue in respect ofinterrupting communications during inter-cell mobility for example.

In NR Release 15, network equipment can update Quasi-Colocation (QCL)assumptions within the same cell (e.g., beam switching). This approach,however, is used only for intra-cell mobility within one cell and is notused for inter-cell mobility. Inter-cell mobility requires RadioResource Control (RRC) signaling (e.g., handover) to reconfigure/updateQCL information or a QCL configuration such as QCL assumptions for a newserving cell, during which UE connectivity and communications areinterrupted. QCL assumptions are indications indicated by the network toa UE, associating two different antenna ports (e.g. reference signals)with a certain type of property (e.g. Doppler shift, Doppler spread,delay spread, average delay, spatial receive information). QCLassumptions are used to indicate to the UE that channel properties (suchas Doppler shift, Doppler spread, delay spread, average delay, spatialreceive information) of one antenna port can be inferred from thechannel properties of another antenna port.

In accordance with a “universal” QCL framework disclosed herein, a UEmaintains a QCL assumption record such as a list, separately fromserving cell configurations, and network equipment instructs the UE asto which QCL assumptions to use for physical layer control/datachannels. Such instruction of the UE by network equipment could be on asemi-static or dynamic basis. A universal QCL framework in which QCLassumptions are maintained separately from cell-specific configurationscould also be described as non-cell-specific, UE-centric, and/orcell-agnostic, for example.

Embodiments could also or instead provide inter-cell resourcemanagement, such as beam management, for intra-frequency dualconnectivity between different cells. Control/data channels couldoriginate from the same cell or different cells. Communication resourceconfiguration that is “externalized” or separated from service cellconfiguration could enable inter-cell mobility to be managed in the sameor a similar manner as intra-cell mobility, through beam management forexample.

FIG. 1 illustrates an example communication system 100 in whichembodiments of the present disclosure could be implemented. In general,the system 100 enables multiple wireless or wired elements tocommunicate data and/or other content. The purpose of the system 100 maybe to provide content (e.g., any one or more of voice, data, video,text) via broadcast, narrowcast, user device to user device, etc. Thesystem 100 may operate efficiently by sharing communication resourcessuch as bandwidth.

In this example, the communication system 100 includes electronicdevices (ED) 110 a-110 c, radio access networks (RANs) 120 a-120 b, acore network 130, a public switched telephone network (PSTN) 140, theInternet 150, and other networks 160. While certain numbers of thesecomponents or elements are shown in FIG. 1 , any reasonable number ofthese components or elements may be included in the system 100.

The EDs 110 a-110 c are configured to operate, communicate, or both, inthe system 100. For example, the EDs 110 a-110 c are configured totransmit, receive, or both via wireless communication channels. Each ED110 a-110 c represents any suitable end user device for wirelessoperation and may include such devices (or may be referred to) as a userequipment/device (UE), wireless transmit/receive unit (WTRU), mobilestation, mobile subscriber unit, cellular telephone, station (STA),machine type communication device (MTC), personal digital assistant(PDA), smartphone, laptop, computer, touchpad, wireless sensor, orconsumer electronics device.

In FIG. 1 , the RANs 120 a-120 b include base stations 170 a-170 b,respectively. Each base station 170 a-170 b is configured to wirelesslyinterface with one or more of the EDs 110 a-110 c to enable access toany other base station 170 a-170 b, the core network 130, the PSTN 140,the Internet 150, and/or the other networks 160. For example, the basestations 170 a-170 b may include (or be) one or more of severalwell-known devices, such as a base transceiver station (BTS), a Node-B(NodeB), an evolved NodeB (eNodeB), a Home eNodeB, a gNodeB or gNB(sometimes called a “gigabit” NodeB), a transmission point (TP), atransmit/receive point (TRP), a site controller, an access point (AP),or a wireless router. Any ED 110 a-110 c may be alternatively or jointlyconfigured to interface, access, or communicate with any other basestation 170 a-170 b, the internet 150, the core network 130, the PSTN140, the other networks 160, or any combination of the preceding.Optionally, the system may include RANs, such as RAN 120 b, wherein thecorresponding base station 170 b accesses the core network 130 via theinternet 150, as shown.

The EDs 110 a-110 c and base stations 170 a-170 b are examples ofcommunication equipment that can be configured to implement some or allof the functionality and/or embodiments described herein. In theembodiment shown in FIG. 1 , the base station 170 a forms part of theRAN 120 a, which may include other base stations, base stationcontroller(s) (BSC), radio network controller(s) (RNC), relay nodes,elements, and/or devices. Any base station 170 a, 170 b may be a singleelement, as shown, or multiple elements, distributed in thecorresponding RAN, or otherwise. Also, the base station 170 b forms partof the RAN 120 b, which may include other base stations, elements,and/or devices. Each base station 170 a-170 b may be configured tooperate to transmit and/or receive wireless signals within a particulargeographic region or area, sometimes referred to as a coverage area. Acell may be further divided into cell sectors, and a base station 170a-170 b may, for example, employ multiple transceivers to provideservice to multiple sectors. In some embodiments a base station 170a-170 b may be implemented as pico or femto nodes where the radio accesstechnology supports such. In some embodiments, multiple-inputmultiple-output (MIMO) technology may be employed having multipletransceivers for each coverage area. The number of RANs 120 a-120 bshown is exemplary only. Any number of RANs may be contemplated whendevising the system 100.

The base stations 170 a-170 b communicate with one or more of the EDs110 a-110 c over one or more air interfaces 190 using wirelesscommunication links e.g. RF, μWave, IR, etc. The air interfaces 190 mayutilize any suitable radio access technology. For example, the system100 may implement one or more channel access methods, such as codedivision multiple access (CDMA), time division multiple access (TDMA),frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), orsingle-carrier FDMA (SC-FDMA) in the air interfaces 190.

A base station 170 a-170 b may implement Universal MobileTelecommunication System (UMTS) Terrestrial Radio Access (UTRA) toestablish an air interface 190 using wideband CDMA (WCDMA). In doing so,the base station 170 a-170 b may implement protocols such as HSPA, HSPA+optionally including HSDPA, HSUPA or both. Alternatively, a base station170 a-170 b may establish an air interface 190 with Evolved UTMSTerrestrial Radio Access (E-UTRA) using LTE, LTE-A, and/or LTE-B. It iscontemplated that the system 100 may use multiple channel accessfunctionality, including such schemes as described above. Other radiotechnologies for implementing air interfaces include IEEE 802.11,802.15, 802.16, CDMA2000, CDMA2000 1×, CDMA2000 EV-DO, IS-2000, IS-95,IS-856, GSM, EDGE, and GERAN. Of course, other multiple access schemesand wireless protocols may be utilized.

The RANs 120 a-120 b are in communication with the core network 130 toprovide the EDs 110 a-110 c with various services such as voice, data,and other services. Understandably, the RANs 120 a-120 b and/or the corenetwork 130 may be in direct or indirect communication with one or moreother RANs (not shown), which may or may not be directly served by corenetwork 130, and may or may not employ the same radio access technologyas RAN 120 a, RAN 120 b or both. The core network 130 may also serve asa gateway access between (i) the RANs 120 a-120 b or EDs 110 a-110 c orboth, and (ii) other networks (such as the PSTN 140, the Internet 150,and the other networks 160). In addition, some or all of the EDs 110a-110 c may include functionality for communicating with differentwireless networks over different wireless links using different wirelesstechnologies and/or protocols. PSTN 140 may include circuit switchedtelephone networks for providing plain old telephone service (POTS).Internet 150 may include a network of computers and subnets (intranets)or both, and incorporate protocols, such as IP, TCP, UDP. EDs 110 a-110c may be multimode devices capable of operation according to multipleradio access technologies, and incorporate multiple transceiversnecessary to support such technologies.

It is contemplated that the communication system 100 as illustrated inFIG. 1 may support an NR cell, which also may be referred to as a hypercell. Each NR cell includes one or more base stations using the same NRcell ID. The NR cell ID is a logical assignment to all physical basestations of the NR cell and may be carried in a broadcastsynchronization signal. The NR cell may be dynamically configured. Theboundary of the NR cell may be flexible, to support dynamically addingbase stations to and/or removing base stations from the NR cell.

In one embodiment, an NR cell may have one or more base stations withinthe NR cell transmitting a UE-specific data channel, which serves a UE.The one or more base stations associated with the UE-specific datachannel are also UE-specific and are transparent to the UE. Multipleparallel data channels within a single NR cell may be supported, witheach data channel serving a different UE for example.

In another embodiment, a broadcast common control channel and adedicated control channel may be supported. The broadcast common controlchannel could be used to carry common system configuration informationtransmitted by all or some base stations that share the same NR cell ID.Each UE can decode information from the broadcast common control channelin accordance with information tied to the NR cell ID. One or more basestations within a NR cell could transmit a UE-specific dedicated controlchannel, which serves a UE and carries UE-specific control informationassociated with the UE. Multiple parallel dedicated control channelswithin a single NR cell may be supported, with each dedicated controlchannel serving a different UE for example. The demodulation of eachdedicated control channel could be performed in accordance with aUE-specific reference signal (RS), the sequence and/or location of whichare linked to the UE ID and/or other UE specific parameters.

In some embodiments, one or more of these channels, including thededicated control channels and the data channels, may be generated inaccordance with a UE-specific parameter, such as a UE ID, and/or an NRcell ID. Further, the UE-specific parameter and/or the NR cell ID couldbe used to differentiate transmissions of the data channels and controlchannels from different NR cells.

An ED, such as a UE, could access the communication system 100 throughat least one of the base stations within an NR cell using a UE dedicatedconnection ID, which allows one or more physical base stationsassociated with the NR cell to be transparent to the UE. The UEdedicated connection ID is an identifier that uniquely identifies the UEin the NR cell. For example, the UE dedicated connection ID could beidentified by a sequence. In some implementations, the UE dedicatedconnection ID is assigned to the UE after an initial access. The UEdedicated connection ID, for example, may be linked to other sequencesand randomizers which are used for physical (PHY) channel generation.

In some embodiments, the UE dedicated connection ID remains the same aslong as the UE is communicating with any base station within the NRcell. In some embodiments, the UE can keep an original UE dedicatedconnection ID when crossing an NR cell boundary. For example, the UEcould only change its UE dedicated connection ID after receivingsignaling from the network.

It should be understood that any number of NR cells may be implementedin the communication system 100. For example, FIG. 2 illustrates twoneighboring NR cells in an example communication system, in accordancewith an embodiment of the present disclosure.

As illustrated in FIG. 2 , each of the two NR cells 282, 284 includesmultiple TRPs that are assigned the same NR cell ID. For example, NRcell 282 includes TRPs 286, 287, 288, 289, 290, and 292, where TRPs 290,292 communicate with an ED, such as UE 294. It should be understood thatother TRPs in NR cell 282 may communicate with UE 294. NR cell 284includes TRPs 270, 272, 274, 276, 278, and 280. TRP 296 is assigned toNR cells 282, 284 at different times, frequencies or spatial directionsand the NR cell ID for TRP 296 may be switched, such as by the system,between the two NR cells 282 and 284. It is contemplated that any number(including zero) of shared TRPs between NR cells may be implemented in asystem.

In one embodiment, the NR cell topology is dynamically updated to adaptto changes in network topology, load distribution, and/or UEdistribution. In some implementations, if the concentration of UEsincreases in one region, then the NR cell may be dynamically expanded toinclude TRPs near the higher concentration of UEs. For example, an NRcell may be expanded to include other TRPs if the concentration of UEslocated at the edge of the NR cell increases above a certain threshold.As another example, an NR cell may be expanded to include a greaterconcentration of UEs located between two hyper cells. In someimplementations, if the traffic load increases significantly at oneregion, the NR cell associated with the region may be expanded toinclude TRPs for the increased traffic load. For example, if the trafficload of a portion of the network exceeds a predetermined threshold, thenthe NR cell ID of one or more TRPs that are transmitting to the impactedportion of the network may be changed.

In another embodiment, the NR cell ID associated with TRP 296 may bechanged from the NR cell ID of NR cell 282 to the NR cell ID of NR cell284. In one implementation, the association of a TRP with different NRcells can be changed periodically, such as every 1 millisecond. Withsuch a flexible NR cell formation mechanism, UEs can be served by thebest TRP(s) so that virtually there are no cell edge UEs.

In yet another embodiment, the shared TRP 296 can reduce interferencefor UEs located at the boundary between the two NR cells 282, 284. UEsthat are located near the boundaries of two NR cells such as 282, 284experience fewer handovers because the shared TRP 296 is associated witheither NR cell at different times, frequencies or spatial directions.Further, as a UE moves between the NR cells 282, 284, the transition isa smoother experience for the user. In one embodiment, the NR cell ID ofthe TRP 296 is changed to transition a UE moving between NR cells 282,284.

TRP selection techniques may be applied to minimize intra-NR cellinterference and inter-NR cell interference. In one embodiment, a TRPsends a downlink channel state information (CSI)-reference symbol (RS).Some pilot (also known as reference signal) ports may be defined suchthat the UEs can measure channel state information and report channelstate information back to the network. A CSI-RS port is a pilot portdefined as a set of known symbols from a sequence transmitted over knownresource elements (for example Orthogonal Frequency DivisionMultiplexing (OFDM) resource elements) for UEs to measure the channelstate. A UE assigned to measure a particular CSI-RS port can measure thetransmitted CSI-RS sequence, measure the associated channel state andreport channel state information back to the network. Network equipment,such as a controller, may select the best TRPs for all served UEs basedon the downlink measurements. In another embodiment, a TRP detects anuplink sounding reference signal (SRS) sequence from a UE in theconfigured time-frequency resources. For example, Constant AmplitudeZero Auto Correlation (CAZAC) sequences such as ZC sequences can be usedas base sequences for SRS. The TRP reports a measurement of the detecteduplink SRS sequence to network equipment, such as a controller. Thecontroller then selects the optimal TRPs for all served UEs based on themeasurements.

Within a communication system, examples of which are described withreference to FIGS. 1 and 2 , embodiments disclosed herein provide forinter-cell UE mobility that does not involve interrupting UEcommunications during reconfiguration.

FIG. 3 is a flow diagram illustrating a method according to anembodiment. The method 300 is a representative example of a method thatcould be performed at a UE.

For the purposes of UE mobility, the operations at 306, 308 are ofparticular relevance. The operation at 306 involves receiving, by a UE,an indication signal from a first base station. The indication signal isfor indicating, to the UE, a communication resource for a secondreference signal from a higher-layer configuration from the first basestation. The second reference signal is associated with a second basestation, and the communication resource for the second reference signalis part of the higher-layer configuration. Various examples of such anindication signal are provided elsewhere herein. The higher-layerconfiguration includes not only a communication resource for a firstreference signal associated with the first base station, but also thecommunication resource for the second reference signal associated with asecond base station. At 308, the UE communicates, with the second basestation, a data transmission or a control signal transmission using arespective data channel or control channel associated with thecommunication resource for the second reference signal. Examples ofcommunication resources, reference signals, higher-layer configurations,and channels are also provided herein.

For instance, in some embodiments a reference signal could be an NZP(non-zero power) CSI-RS or a Synchronization Signal (SS) in an SS/PBCH(Physical Broadcast Channel) block. An SS/PBCH block is also referred toas an SS block or SSB. Antenna beams represent one example of acommunication resource. Other examples of a communication resourceinclude resources that are differentiated or distinguished from eachother by one, or some combination, of time, frequency, code, sequence,antenna port, and layer. Other examples may be or become apparent tothose skilled in the art.

Examples of a higher-layer configuration include a configuration that isprovided to a UE in RRC signaling, and a beam management module orconfiguration. More generally, a higher-layer configuration asreferenced herein relates to a configuration message carrying someinformation in the form of so-called information elements (IEs) carryingparameters related to operating in the cellular network, and is providedby network equipment to a UE.

Embodiments could include other operations as well, including any one ormore of those shown by way of example in FIG. 3 . A method could includereceiving 302, by the UE, the higher-layer configuration from the firstbase station. A method could also or instead involve performing, by theUE, channel measurements for a channel used for communicating a datatransmission or a control signal transmission with the first basestation, and communicating, by the UE to the first base station, anindication of the channel measurements. This is illustrated at 304.Similar operations in connection with the second base station are shownat 310. As illustrated by 310, a method could also or instead involveperforming, by the UE, channel measurements for a channel used forcommunicating the data transmission or the control signal transmissionwith the second base station, and communicating, by the UE to the secondbase station, an indication of the channel measurements.

Operations could also or instead be repeated multiple times. Forexample, the UE could transition from the second base station to anotherbase station, which could be the first base station or a different basestation in a communication network. In this case, the UE could receivean indication signal from the second base station and then communicatewith the first base station or the different base station.

Embodiments could include other features, such as any one or more of thefollowing, in any combinations:

the indication signal is or includes Quasi-Colocation (QCL) information;

the indication signal is or includes a Medium Access Control-ControlElement (MAC-CE) indication of the communication resource for the secondreference signal;

the indication signal is or includes a Downlink Control Information(DCI) indication of the communication resource for the second referencesignal;

the indication signal is or includes an RRC indication of thecommunication resource for the second reference signal;

the higher-layer configuration further includes a communication resourcefor beam failure recovery.

FIG. 4 is a flow diagram illustrating a method according to anotherembodiment. The method 400 is a representative example of a method thatcould be performed at network equipment such as a base station.

From a network-side perspective, the operations at 408, 410 are ofparticular relevance to UE mobility. The operation at 408 involvesgenerating an indication signal. The indication signal is generated by afirst base station, and is for indicating to a UE a communicationresource for a second reference signal. The communication resource forthe second reference signal is part of a higher-layer configuration fromthe first base station to the UE. As noted above with reference to FIG.3 , various examples of such an indication signal are provided elsewhereherein. The higher-layer configuration includes not only a communicationresource for a first reference signal associated with the first basestation, but also the communication resource for the second referencesignal associated with a second base station. At 410, the first basestation transmits the indication signal to the UE, to enable the UE tocommunicate with the second base station, a data transmission or acontrol signal transmission using a respective data channel or controlchannel associated with the communication resource for the secondreference signal. Examples of communication resources, referencesignals, and channels are also provided elsewhere herein.

Embodiments could include other operations as well, including any one ormore of those shown by way of example in FIG. 4 . A method could includetransmitting 402, by the first base station, the higher-layerconfiguration to the UE. A method could also or instead involvereceiving 404, by the first base station from the UE, an indication ofchannel measurements performed by the UE for a channel used forcommunicating a data transmission or a control signal transmission withthe first base station. UE mobility decisions could be made based atleast in part on such channel measurements, as shown at 406, and theindication signal could be generated and transmitted at 408, 410responsive to a determination that the UE is to transition from the basestation to another base station, or possibly even between differentresources such as beams associated with the first base station.

Operations could also or instead be repeated multiple times, fordifferent UEs for example.

Embodiments could include other features, such as any one or more of thefollowing, in any combinations:

the indication signal is or includes QCL information;

the indication signal is or includes a MAC-CE indication of thecommunication resource for the second reference signal;

the indication signal is or includes a DCI indication of thecommunication resource for the second reference signal;

the indication signal is or includes an RRC indication of thecommunication resource for the second reference signal;

the higher-layer configuration further includes a communication resourcefor beam failure recovery.

FIGS. 3 and 4 and the descriptions thereof are illustrative ofembodiments. Other embodiments could involve performing additional,fewer, and/or different operations in a similar or different order. Theillustrated operations and/or others could be performed in any ofvarious ways. Such variations of these and other embodiments aredisclosed herein or may otherwise be or become apparent from the presentdisclosure. Several detailed examples are also provided below.

Some embodiments enable inter-cell mobility using communication resourcemanagement such as beam management. FIG. 5 is a block diagramillustrating coverage areas or cells in a wireless communicationnetwork. The example wireless communication network 500 includes basestations 522, 524, 526, 528, 530, 532, 534, providing respectivecoverage areas or cells 502, 504, 506, 508, 510, 512, 514. Although onlyone base station per cell is shown in FIG. 5 , in other embodiments acell could include multiple base stations such as multiple TRPs, forexample. It should also be appreciated that other features of FIG. 5could be different in other embodiments. Cells could have differentshapes and/or sizes, more or fewer cells could be provided, and/or cellscould be arranged in a different pattern than shown, for example.

To provide context for UE mobility through beam management as anillustrative example, antenna beams 0 to 7 and 0 to 14 are shown in FIG.5 for the base stations 524, 534, respectively. The other base stations522, 526, 528, 530, 532 could have beam patterns that are similar to ordifferent from those shown. Such features as the number of beamsprovided by any base station, beam widths, beam directions, and/or beamcoverage could be different in other embodiments. Inter-cell mobilityherein refers to mobility of a UE between different cells, rather thanmobility between beams or network equipment such as TRPs that are partof the same cell.

FIG. 6 is a block diagram illustrating two adjacent coverage areas orcells in a wireless communication network 600. The adjacent cells 602,604 provided by base stations 606, 608, respectively, could be any twoadjacent cells as shown in FIG. 5 or FIG. 2 , for example. As notedabove for FIG. 5 , in other embodiments a cell could include multiplebase stations such as multiple TRPs, for example, and other featuressuch as shapes and/or sizes of cells, number of cells, cell pattern,number of beams provided by any base station, beam widths, beamdirections, and/or beam coverage could be different in otherembodiments.

Four antenna beams 0 to 3 and 10 to 13 are shown in FIG. 6 , toillustrate antenna beam identifiers such as beam indices that are uniqueat least between adjacent cells. Three UE positions A, B, C are alsoshown. UE mobility between beams 0 and 1 as a UE moves from position Ato position B could involve beam management in accordance with NRRelease 15. This is an example of intra-cell UE mobility. UE movementfrom position B to position C is an example of inter-cell UE mobility,and normally involves interrupting UE communications. According toembodiments of the present disclosure, however, inter-cell mobilitycould involve beam management, for the UE to switch from antenna beam 1to antenna beam 11, without having to complete a reconfigurationprocedure during which UE communications are interrupted.

A beam switching indication or command is an example of an indicationsignal that could be transmitted to the UE by base station 606 totransition the UE from base station 606 (beam 1) to base station 608(beam 11). The indication signal could include beam index 11 and/or someother identifier of antenna beam 11 for example. The UE could switchfrom beam 1 to beam 11 in response to the indication signal, therebyenabling inter-cell mobility between the different cells 602, 604 whileavoiding an interruption in UE communications.

To support this type of inter-cell mobility, the base station 606,during initial access by the UE at position A for example, could includeinformation associated with both the base station 606 and the basestation 608 in a higher-layer configuration that is signaled orotherwise provided to the UE. For example, such a higher-layerconfiguration could include not only a communication resource (e.g.,beam 0) for a first reference signal associated with the base station606, but also a second communication resource (e.g., beam 11) for asecond reference signal associated with the base station 608.Information associated with other adjacent neighboring base stations ofthe base station 606 could also be included in the higher-layerconfiguration. The UE then has the information it needs when moving fromone cell to a neighboring cell.

Other configurations and/or UE mobility between other cells could behandled in a similar manner. After the UE has moved to position C, forexample, the base station 608 could provide to the UE informationassociated with neighbors of the base station 608, or possibly onlyneighbors other than the base station 606, for which the UE already hasconfiguration information. More generally, a base station in a targetcell into which a UE moves could provide neighboring base station orcell information to a UE for all neighboring base stations or cells ofthe target base station or cell, with the possible exception of theprevious serving cell or base station or any other neighboring basestations or cells for which the UE already has configurationinformation. In some embodiments, information for all neighbors could beprovided to a UE, and the UE could ignore information for any neighborsfor which it already has information.

It should be appreciated, however, that there could be cases withupdates to a UE's higher-layer configuration, and other cases with nosuch updates.

FIG. 7 is a signaling diagram illustrating inter-cell mobility signalingaccording to an embodiment. FIG. 7 relates to an example 700 in which aUE 702 transitions from a serving cell or source cell that is servicedby a source gNB 704 to a target a target cell that is serviced by atarget gNB 706. In FIG. 7 , it is presumed that initial access andconfiguration has already been completed.

Operations 710, 712 represent downlink communication between the UE 702and the source gNB 704. Data transmission 712 and control signaltransmission 710 from the source gNB 704 to the UE 702 use respectivedata channel and control channel, shown by way of example as a PhysicalDownlink Shared Channel (PDSCH) and a Physical Downlink Control Channel(PDCCH). These channels are associated with reference signals that arein turn associated with the source gNB 704.

The UE 702 performs physical layer (layer 1 or “L1”) channelmeasurements, examples of which are disclosed elsewhere herein, andprovides an L1 measurement report to the source gNB 704 at operation714. Based on the channel measurements, the source gNB determineswhether the UE 702 should be transitioned to the target gNB 706. Forexample, the source gNB 704 could determine whether the UE 702 should betransitioned to the target gNB 706 by comparing channel measurements toone or more thresholds, and making a determination based on whether thechannel measurements are above or below the threshold(s).

At operations 716, 718, FIG. 7 shows an example of signaling between thegNBs 704, 706, so that the target gNB 706 is ready to take on the UE702. A TCI State update as shown at 720 references a communicationresource of the target gNB 706, and is an example of an indicationsignal that is also described elsewhere herein.

After the TCI State update at operation 720, the UE 702 communicates,with the target gNB 706, a data transmission and a control signaltransmission using the respective data channel (PDSCH) and controlchannel (PDCCH), at operations 722, 724. The PDSCH and PDCCH at 722, 724are associated with reference signals that are in turn associated withthe target gNB 706. UE mobility in FIG. 7 involves only a TCI Stateupdate at operation 720, rather than a reconfiguration during which UEcommunications are interrupted.

FIG. 8 is a signaling diagram illustrating an example of higher-layerconfiguration signaling and inter-cell mobility signaling in accordancewith some embodiments. In the example 800, a UE 802 initiates an accessprocedure at operation 810. The gNB 804 responds with an RRCReconfiguration message at 812. The RRC Reconfiguration message,however, includes not only information associated with the gNB 804itself, but also information associated with one or more neighboringgNBs. For example, the RRC Reconfiguration message could be considered aform of a higher-layer configuration received by the UE 802 from the gNB804, including a communication resource for a first reference signalassociated with the gNB and a communication resource for a secondreference signal associated with a different gNB.

The following is an example of an RRC Reconfiguration InformationElement (IE) that could be sent from the gNB 804 to the UE 802 atoperation 812 to provide the UE with a higher-layer configuration thatincludes information for both the gNB 804 and at least one other gNB:

RRCReconfiguration-IEs ::=   {  radioBearerConfig      RadioBearerConfig  . . .  beamManagementConfig     BeamManagementConfig    . . .  }

The UE 802 copies information from the higher-layer configuration intoone or more memory devices, and sends an RRC Reconfiguration Completemessage to the gNB 804 at operation 814. In some embodiments, one ormore internal UE variables are used to store such information in UEmemory, and examples of such variables are provided elsewhere herein.

In a TCI State Activation message at operation 816, the gNB 804 informsthe UE 802 as to which TCI states the UE should track. This could be ina MAC-CE command or indication, a DCI command or indication, or an RRCcommand or indication, for example. After TCI state activation, the UE802 communicates with the gNB 804 using control and data channels PDCCHand PDSCH, at operations 818, 820. At some later time, a new TCI StateActivation message, to transition the UE 802 to different resources suchas different beams of the gNB 804, or to another gNB in a differentcell, is sent from the gNB 804 to the UE 802 at operation 822. Inresponse to the new TCI State Activation message at 822 the UE 802performs beam switching. The TCI State Activation message at operation822 is an example of an indication signal as referenced elsewhereherein.

FIG. 9 is a signaling diagram illustrating another example ofhigher-layer configuration signaling and inter-cell mobility signaling.In the example 900, a UE 902 receives a higher-layer configuration froma BS1 904 in RRC signaling 910 that includes information associated withthe serving base station BS1 904 and information associated with aneighboring base station BS2 906. Configuration and channel measurementare represented at operations 920, 922, respectively, and a measurementreport is transmitted by the UE 902 to the serving base station BS1 904at operation 912. The measurement report could be raw or filtered.

Communications between the UE 902 and the serving base station BS1 904could be ongoing, but are not shown in FIG. 9 in order to avoidcongestion in the drawing.

As the UE moves, represented by the dashed line in FIG. 9 , mobilitydecisions are made by the serving base station BS1 904, as shown atoperation 924. If the serving base station BS1 904 determines that theUE 902 should be transitioned to a different communication resource, inparticular an antenna beam in the example shown in FIG. 9 , then anindication signal in the form of a beam indication at operation 914 istransmitted to the UE by the base station. A beam indication could be ina MAC-CE command or indication, a DCI command or indication, or an RRCcommand or indication, for example. The UE 902 performs beam switchingin accordance with the beam indication, and then communicates with abase station using the new beam. Communications at operation 916 afterbeam switching could be with the same serving base station BS1 904 oranother base station in the same cell for intra-cell mobility, but forillustrative purposes the base station BS2 906 is intended to representa base station that provides service in a different cell.

Although not shown in FIG. 9 , the serving base station BS1 904 couldexchange message with the base station BS2 906 to prepare the basestation BS2 906 to take over the UE 902. An example of this is shown inFIG. 7 .

FIG. 9 also illustrates that communications could involve uplink (UL)and/or downlink (DL) transmissions. Examples herein refer primarily toDL communications from a base station to a UE, but embodiments couldalso or instead be applied to UL communications.

Aspects of a universal QCL framework and inter-cell beam management arereferenced herein, and will now be discussed by way of further detailedexamples. In this application, “universal” is intended to mean that theQCL framework is intended to operate for source and neighbor cells, orequivalently for serving and non-serving cells.

With regard first to universal QCL framework, it is noted that in NRRelease 15, TCI state tables are maintained with PDSCH configurationobjects. PDSCH-Config are defined for given serving cells and BWPs asshown below:

-- ASN1START -- TAG-PDSCH-CONFIG-START PDSCH-Config::= SEQUENCE { dataScramblingIdentityPDSCH   INTEGER (0..1023)   OPTIONAL, -- Need S dmrs-DownlinkForPDSCH-MappingTypeA    SetupRelease{DMRS-DownlinkConfig}    OPTIONAL, -- Need M dmrs-DownlinkForPDSCH-MappingTypeB    SetupRelease{DMRS-DownlinkConfig}    OPTIONAL, -- Need M  

 

 

 tci-StatesToReleaseList       SEQUENCE(SIZE(1..MaxNrofTCI-States)) OFTCI-StateId     OPTIONAL, -- Need N  ... } -- TAG-PDSCH-CONFIG-STOP --ASN1STOP

The above object is an RRC IE used to configure parameters for a UE toreceive a channel, such as a PDSCH. The item in bold and underlineformatting includes a list of QCL assumptions. This configuration iscurrently for a serving cell, and therefore requires reconfigurationwhen an UE moves to a different cell.

Optional fields in an RRC IE can be provided with tags specifying the UEbehaviour with respective to a given field's presence or absence whenthe UE receives a higher-layer signaling message with that RRC IE. “NeedS” means that the UE behaviour is specified if the field is absent.“Need M” means that the UE behaviour is to maintain its current value ifthe field is absent. “Need N” means that the UE behaviour is to take noaction if the field is absent. “Need R”, which is not in the aboveexample but appears below, means that the UE behaviour is to release thecurrent value if the field is absent.

Fields in an RRC IE can be provided with conditional tags whichpredicate the presence of a given field on a certain condition to beverified. For example, if conditionTag is the condition tag associatedto a field, then “Cond condition Tag” means that the presence of thefield is conditional on conditionTag being verified. “CondC conditionTag” means that the presence of the field is conditional to the settinggiven by conditionTag. “CondM condition Tag” means that the presence ofthe field is conditional to the field conditionTag being included in themessage.

According to some embodiments, a variable for the UE to maintain aTCI-state list/QCL assumptions separately from cell-specificconfiguration is introduced. For example, RRC objects could reference anentry in a TCI-state list maintained by the UE, as shown below, in whichan example of a new variable is highlighted in bold and underline:

-- ASN1START -- TAG-VAR-TCI-STATE-START

 

 --

 

 

TCI-State::= SEQUENCE {  tci-StateId INTEGER(0..maxNrofTCI-States-1), qcl-Type1 QCL-Info,  qcl-Type2 QCL-Info,  ... } QCL-Info::= SEQUENCE { cell    ServCellIndex,  bwp-Id   BWP-Id,  referencesignal    CHOICE {  csi-rs  NZP-CSI-RS-ResourceId,   ssb        SSBIndex  },  qcl-Type ENUMERATED{typeA, typeB, typeC, typeD}  } -- TAG-VAR-TCI-STATE-STOP --ASN1STOP

The following provides another example of an RRC procedure for TCI statelist configuration, with an example new item highlighted in bold andunderline:

-- ASN1START -- TAG-RRCRECONFIGURATION-START RRCReconfiguration-IEs::=   SEQUENCE{ radioBearerConfig    RadioBearerConfig  OPTIONAL, -- Need M secondaryCellGroup   OCTET STRING (CONTAINING CellGroupConfig)  OPTIONAL, -- Need M  measConfig           MeasConfig OPTIONAL, -- NeedM  

 

 lateNonCriticalExtension  OCTET STRING   OPTIONAL, nonCriticalExtension    RRCReconfiguration-v1530-IEs   OPTIONAL } --TAG-RRCRECONFIGURATION-STOP -- ASN1STOP

The following procedure is applied by network equipment in anembodiment:

-   -   to ensure that, whenever the UE has a PDSCH-Config, it includes        a tci-StateId for the PDSCH transmission to be received;    -   to ensure that, whenever the UE has a ControlResourceSet, it        includes a tci-StateId for the PDCCH transmission to be        received;        The UE applies the following procedure, in an embodiment:    -   1> for each tci-StateId included in the received        tci-StateToAddModList:        -   2> if an entry with the matching tci-StateId exists in the            tci-StateToAddModList within the VarTciStateConfig, for this            entry:            -   3> reconfigure the entry with the value received for                this TCI-State;        -   2> else:            -   3> add a new entry for the received TCI-State to the                tci-StateToAddModList within VarTciStateConfig.

In some embodiments, a variable for the UE to maintain a TCI-state listseparately is introduced, and RRC objects reference an entry in the TCIstate list maintained by the UE. See TCI-StateId in the item highlightedby bold and underline below:

-- ASN1START -- TAG-PDSCH-CONFIG-START PDSCH-Config::= SEQUENCE { dataScramblingIdentityPDSCH     INTEGER (0..1023)   OPTIONAL, -- Need S dmrs-DownlinkForPDSCH-MappingTypeA     SetupRelease{DMRS-DownlinkConfig}    OPTIONAL, -- Need M dmrs-DownlinkForPDSCH-MappingTypeB     SetupRelease{DMRS-DownlinkConfig}    OPTIONAL, -- Need M  

 

 

 

 tci-StatesToReleaseList SEQUENCE(SIZE(1..MaxNrofTCI-States)) OF TCI-StateId   OPTIONAL, -- Need N }  ... -- TAG-PDSCH-CONFIG-STOP --ASN1STOP

TCI-StateId is an identifier of a Transmission Configuration Indicatorstate. A TCI state is an IE that associates a downlink reference signalwith a QCL assumption (e.g. delay spread, average delay, Doppler spread,Doppler shift, Spatial Rx filter). The TCI-StateId is used to uniquelyidentify a given downlink reference signal and a set of one or more QCLassumptions. When a UE is provided with a TCI-StateId in thePDSCH-Config, the UE can assume that for any PDSCH DMRSs transmitted aspart of the PDSCH transmission, the UE can perform channel estimationbased on the QCL assumptions it derived from the downlink referencesignal indicated in the TCI-State identified by TCI-StateId.

Inter-cell beam management could involve “cell-transparent” beamswitching, in which a UE switches between beams that are associated withdifferent cells, without first completing RRC reconfiguration andexperiencing an interruption in communications.

In NR Release 15, QCL information supplies a reference to thecorresponding serving cell configuration. If QCL information is based onSSBs, then it includes a reference to the serving cell configuration. IfQCL information is based on CSI-RSs, then there is no need for physicalcell identity. An example of QCL information is provided below, andincludes a physical cell identity in the form of a serving cell index,which is highlighted in bold and underline below:

-- ASN1START -- TAG-VAR-TCI-STATE-START VarTciStateConfig::=    SEQUENCE{  --TCI state list  tci-StatesToAddModList SEQUENCE(SIZE(1..maxNrofTCI-States)) OF TCI-State OPTIONAL, -- Need N }TCI-State:: = SEQUENCE {  tci-StateId INTEGER(0..maxNrotTCI-States-1), qcl-Type1 QCL-Info,  qcl-Type2 QCL-Info,  ... } QCL-Info::= SEQUENCE { 

 bwp-Id BWP-Id,  referencesignal    CHOICE {   csi-rs                   NZP-CSI-RS-ResourceId,   ssb               SSBIndex },  qcl-Type  ENUMERATED{typeA, typeB, typeC, typeD} } --TAG-VAR-TCI-STATE-STOP -- ASN1STOP

According to some embodiments, if QCL information is based on SSBs, thenthe physical cell identity and ssbFrequency are included for uniqueidentification, and if QCL information is based on CSI-RSs then there isno need for physical cell identity. An example is shown below. See inparticular the elements highlighted in bold and underline below:

-- ASN1START -- TAG-VAR-TCI-STATE-START VarTciStateConfig::=    SEQUENCE{  --TCI state list  tci-StatesToAddModList SEQUENCE(SIZE(1..maxNrofTCI-States)) OF TCI-State    OPTIONAL, -- Need N }TCI-State::= SEQUENCE {  tci-StateId INTEGER(0..maxNrotTCI-States-1), qcl-Type1 QCL-Info,  qcl-Type2 QCL-Info,  ... } QCL-Info::= SEQUENCE { bwp-Id  BWP-Id,  referencesignal    CHOICE {  csi-rs            NZP-CSI-RS-ResourceId,

 },  qcl-Type ENUMERATED{typeA, typeB, typeC, typeD}  ... }

 

 

-- TAG-VAR-TCI-STATE-STOP -- ASN1STOP

In some embodiments, a Serving cell ID field in TCI Stateactivation/deactivation for UE-specific PDSCH MAC-CE command is nolonger required. The following is an example:

R R R R R R BWP ID TCI 7 TCI 6 TCI 5 TCI 4 TCI 3 TCI 2 TCI 1 TCI 0 . . .TCI TCI TCI TCI TCI TCI TCI TCI N-1 N-2 N-3 N-4 N-5 N-6 N-7 N-8

In the above example, each TCI field could have a value of 0 or 1 toindicate to a UE which TCI states the UE should track. A value of 1could indicate an active TCI state, for example, although otheractive/inactive indication or designation values could be used. The UEdoes not need to distinguish between or be aware of whether referencesignals are associated with a serving/source cell or a neighbor/targetcell.

For large values of the number of TCI states N (e.g., N>256), TCI-StateGroup activation for a UE-specific PDSCH MAC-CE command could include,for example, TCI group size: Maximum Number of TCI states in group, TCIgroup start: Maximum Number of TCI states/TCI group size, and TCI-stateID i=TCI group start*TCI group size+n, as in the following example:

TCI group start BWP ID TCI group size TCI group start TCI (i + TCI groupsize − 1) . . . TCI (i + 2) TCI (i + 1) TCI i

A TCI-state whose ID is outside the TCI-state group activation would beTCI-state inactive. In an embodiment, for a TCI-state whose ID is insidethe TCI-state group activation, the TCI-state is active if thecorresponding TCI field (“TCI (i+x)” in the above example) is set to 1,and the TCI-state is inactive if the corresponding TCI field is set to0. Other active/inactive indication or designation values could be used.

As noted elsewhere herein, in NR Release 15 beam management is afunction performed within a cell. Beam Failure Detection and BeamFailure Recovery are defined for a given serving cell configuration, andresources used for beam management are defined in Csi-MeasConfig. FIG.10 is a block diagram illustrating an example serving cell configurationstored at a UE. In FIG. 10 , the circled elements represent resourcesused for beam management.

In accordance with some embodiments, beam management resourcedefinitions are moved outside of, or “externalized” from, serving cellconfiguration. An example is shown below, in which elements in bold anditalic are to be moved outside of service cell configuration, to provideresource configurations that need not change based on UE mobilitybetween different cells.

   -- ASN1START  -- TAG-CSI-MEAS-CONFIG-START CSI-MeasConfig::= SEQUENCE {   

 

 

  nzp-CSI-RS-ResourceToReleaseList SEQUENCE(SIZE(1..MaxNrofNZP-CSI-RS- Resources)) OF NZP-CSI-RS-ResourceId OPTIONAL, -- Need N   

 

  nzp-CSI-RS-ResourceSetToReleaseList SEQUENCE(SIZE(1..MaxNrofNZP-CSI- RS-ResourceSets)) OF NZP-CSI-RS-ResourceSetId OPTIONAL, -- Need N  csi-IM-ResourceToAddModList SEQUENCE(SIZE(1..MaxNrofCSI-IM-Resources)) OF CSI-IM-Resource OPTIONAL, -- Need N  csi-IM-ResourceToReleaseList SEQUENCE(SIZE(1..MaxNrofCSI-IM-Resources)) OF CSI-IM-ResourceId OPTIONAL, -- Need N  csi-IM-ResourceSetToAddModList SEQUENCE(SIZE(1..MaxNrofCSI-IM- ResourceSets)) OF CSI-IM-ResourceSet OPTIONAL, -- Need N  csi-IM-ResourceSetToReleaseList SEQUENCE(SIZE(1..MaxNrofCSI-IM- ResourceSets)) OF CSI-IM-ResourceSetId OPTIONAL, -- Need N   

 

 

 

  csi-SSB-ResourceSetToReleaseList SEQUENCE(SIZE(1..MaxNrofCSI-SSB- ResourceSets)) OF CSI-SSB-ResourceSetId OPTIONAL, -- Need N  csi-ResourceConfigToAddModList SEQUENCE(SIZE(1..MaxNrofCSI- ResourceConfigurations)) OF CSI-ResourceConfig OPTIONAL, -- Need N  csi-ResourceConfigToReleaseList SEQUENCE(SIZE(1..MaxNrofCSI- ResourceConfigurations)) OF CSI-ResourceConfigId OPTIONAL, -- Need N  csi-ReportConfigToAddModList SEQUENCE(SIZE(1..MaxNrofCSI- ReportConfigurations)) OF CSI-ReportConfig OPTIONAL, -- Need N  csi-ReportConfigToReleaseList SEQUENCE(SIZE(1..MaxNrofCSI- Reportconfigurations)) OF CSI-ReportConfigId OPTIONAL, -- Need N  reportTriggerSize INTEGER (0..6) OPTIONAL, -- Need M  aperiodicTriggerStateList SetupRelease{CSI-AperiodicTriggerStateList} OPTIONAL, -- Need M  semiPersistentOnPUSCH-TriggerStateList SetupRelease{CSI- SemiPersistentOnPUSCH-TriggerStateList} OPTIONAL, -- Need M   ...  } -- TAG-CSI-MEAS-CONFIG-STOP  -- ASN1STOP

An example in which beam management resource definitions are moved outof serving cell configuration is shown below, with a new variable and anew field highlighted in bold and underline. The bold and underlinedline under NZP-CSI-RS-Resource below highlights a field that could beadded to specify information that may be needed as a result of movingthe resource definitions out of serving cell configuration.

-- ASN1START -- TAG-VAR=BEAM-MANAGEMENT-CONFIG-STARTVarBeamManagementConfig::=SEQUENCE {  --NZP CSI-RS resources beamManagementCsirsResourcesToAddModListSEQUENCE(SIZE(1..maxNrofNZP-CSI-RS-Resources)) OF NZP-CSI-RS-Resource OPTIONAL,  --NZP CSI-RS resource sets beamManagementCsirsResourceSetToAddModListSEQUENCE(SIZE(1..maxNrofNZP-CSI-RS-ResourceSets)) OF NZP-CSI-RS-ResourceSet OPTIONAL,  --CSI-SSB resource sets beamManagementCsissbResourceSetToAddModListSEQUENCE(SIZE(1..maxNrofCSI-SSB-ResourceSets)) OF CSI-SSB-ResourceSetOPTIONAL } -- TAG-VAR-BEAM-MANAGEMENT-CONFIG-STOP -- ASN1STOP-- ASN1START -- TAG-NZP-CSI-RS-RESOURCE-STARTNZP-CSI-RS-Resource::= SEQUENCE { nzp-CSI-RS-ResourceId NZP-CSI-RS-ResourceId, absoluteFrequencyCSI-RS ARFCN-ValueNR, resourceMapping CSI-RS-ResourceMapping, powerControlOffset INTEGER (−8..15), powerControlOffsetSS ENUMERATED {db−3, db0, db3, db6} OPTIONAL, -- NeedR  scramblingID ScramblingId, periodicityAndOffset CSI-ResourcePeriodicityAndOffset OPTIONAL, -- CondPeriodicOrSemiPersistent qcl-InfoPeriodicCSI-RS TCI-StateId OPTIONAL, -- Cond Periodic  ... }-- TAG-NZP-CSI-RS-RESOURCE-STOP -- ASN1STOP

Source/Neighbour cell reference resources could be maintained in aseparate list by a UE. Network equipment could configure UE with a givenset of resources (e.g. SSB/CSI-RS), for example.

An example RRC IE and procedure that could be used if an RRCReconfiguration message carries a beamManagementConfig object are shownbelow, and cause a UE to copy content to a variablevarBeamManagementConfig, referenced in an example above. See inparticular the elements in bold and underline.

  -- ASN1START -- TAG-RRCRECONFIGURATION-STARTRRCReconfiguration-IEs: SEQUENCE { radioBearerConfig RadioBearerConfig OPTIONAL, -- Need M secondaryCellGroup OCTET STRING (CONTAINING CellGroupConfig)OPTIONAL, -- Need M  measConfig MeasConfig OPTIONAL, -- Need M beamManagementConfig BeamManagementConfig OPTIONAL, -- Need N lateNonCriticalExtension OCTET STRING OPTIONAL, nonCriticalExtension RRCReconfiguration-v1530-IEs }BeamManagementConfig::= SEQUENCE {  --NZP CSI-RS resources beamManaqementCsirsResourcesToAddModListSEQUENCE(SIZE(1..maxNrofNZP-CSI-RS-Resources)) OF NZP-CSI-RS-Resource OPTIONAL,  --NZP CSI-RS resource sets beamManaqementCsirsResourceSetToAddModListSEQUENCE(SIZE(1..maxNrofNZP-CSI-RS-ResourceSets)) OF NZP-CSI-RS-ResourceSet OPTIONAL,  --CSI-SSB resource sets beamManagementCsissbResourceSetToAddModListSEQUENCE(SIZE(1..maxNrofCSI-SSB-ResourceSets)) OF CSI-SSB-ResourceSetOPTIONAL } -- TAG-RRCRECONFIGURATION-STOP -- ASN1STOP

According to procedure in some embodiments, a UE shall:

-   -   1> for each nzp-CSI-RS-ResourceId included in the received        beamManagementCsirsResourcesToAddModList:        -   2> if an entry with the matching nzp-CSI-RS-ResourceId            exists in the beamManagementCsirsResourcesToAddModList            within the VarBeamManagementConfig, for this entry:            -   3> reconfigure the entry with the value received for                this bnzp-CSI-RS-ResourceId;        -   2> else:            -   3> add a new entry for the received                nzp-CSI-RS-ResourceId to the                beamManagementCsirsResourcesToAddModList within                VarBeamManagementConfig.

In some embodiments, a UE shall:

-   -   1> for each nzp-CSI-RS-ResourceSetId included in the received        beam ManagementCsirsResourceSetToAddModList:        -   2> if an entry with the matching nzp-CSI-RS-ResourceSetId            exists in the beam ManagementCsirsResourceSetToAddModList            within the VarBeamManagementConfig, for this entry:            -   3> reconfigure the entry with the value received for                this nzp-CSI-RS-ResourceSetId;        -   2> else:            -   3> add a new entry for the received                nzp-CSI-RS-ResourceSetId to the beam                ManagementCsirsResourceSetToAddModList within                VarBeamManagementConfig.

A UE shall, in some embodiments:

-   -   1> for each csi-SSB-ResourceSetId included in the received beam        ManagementCsissbResourceSetToAddModList:        -   2> if an entry with the matching csi-SSB-ResourceSetId            exists in the beamManagementCsissbResourceSetToAddModList            within the VarBeamManagementConfig, for this entry:            -   3> reconfigure the entry with the value received for                this csi-SSB-ResourceSetId;        -   2> else:            -   3> add a new entry for the received                csi-SSB-ResourceSetId to the                beamManagementCsissbResourceSetToAddModList within                VarBeamManagementConfig.

Some embodiments could involve moving candidate beam resourcedefinitions out of serving cell configuration for Beam Failure Recovery.This could be implemented in combination with or independently fromother features disclosed herein. Shown below, in bold and italic, areexamples of definitions that could be moved out of serving cellconfiguration.

  -- ASN1START -- TAG-BEAM-FAILURE-RECOVERY-CONFIG-STARTBeamFailureRecoveryConfig::= SEQUENCE { rootSequenceIndex-BFR INTEGER (0..137) OPTIONAL, -- Need M rach-ConfigBFR RACH-ConfigGeneric OPTIONAL, -- Need M rsrp-ThresholdSSB RSRP-Range OPTIONAL, -- Need M  

 

 ssb-perRACH-Occasion ENUMERATED{oneEighth, oneFourth, oneHalf, one, two,four, eight, sixteen} OPTIONAL, -- Need M ra-ssb-OccasionMaskIndex INTEGER(0..15) OPTIONAL, -- Need M recoverySearchSpaceId SearchSpaceId OPTIONAL, -- Cond CF-BFR ra-Prioritization RA-Prioritization OPTIONAL, -- Need R beamFailureRecoveryTimer ENUMERATED{ms10, ms20, ms40, ms80, ms100,ms150, ms200} OPTIONAL, -- Need M  ...,  [[ msg1-SubcarrierSpacing-v1530 SubcarrierSpacing    OPTIONAL -- Need M ]] }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-- TAG-BEAM-FAILURE-RECOVERY-CONFIG-STOP -- ASN1STOP

One or more UE variables maintaining a dedicated RS list for BeamFailure Recovery could be introduced, and an example is shown in boldand underline below.

  -- ASN1START -- TAG-VAR=BEAM-FAILURE-RECOVERY-CONFIG-STARTVarBeamFailureRecoveryConfig::= SEQUENCE { bfr-DedicatedRSList SEQUENCE(SIZE(1..maxNrofCandidateBeams)) OF BFR-DedicatedResource OPTIONAL } BFR-DedicatedResource::= SEQUENCE { bfr-CandidateBeamIndex INTEGER(1..maxNrofCandidateBeams), bfr-CandidateBeam BFR-CandidateBeam,  ... }BFR-CandidateBeam::= CHOICE {  ssb BFR-SSB-Resource, csi-RS BFR-CSIRS-Resource } BFR-SSB-Resource::= SEQUENCE { ssb SSB-Index,  ra-PreambleIndex INTEGER(0..63),  ... }BFR-CSI-RS-Resource::= SEQUENCE {  csi-RS NZP-CSI-RS-ResourceId, ra-OccasionList SEQUENCE(SIZE(1..maxRAOccasionsPerCSIRS)) OFINTEGER(0..maxRAOccasions−1) OPTIONAL, -- Need R ra-PreambleIndex INTEGER(0..63) OPTIONAL, -- Need R }-- TAG-VAR-BEAM-FAILURE-RECOVERY-CONFIG-STOP -- ASN1STOP

SSB/NZP CSI-RS resource definition for BFR, for example, could includesuch information as time/frequency location and QCL assumptions, asillustrated by the elements highlighted in bold and underline below.

  -- ASN1START -- TAG-VAR=BEAM-FAILURE-RECOVERY-CONFIG-STARTBFR-SSB-Resource::= SEQUENCE {  ssb SSB-Index, ssbFrequency ARFCN-ValueNR,  ra-PreambleIndex INTEGER(0..63),  ... }BFR-CSI-RS-Resource::= SEQUENCE {  csi-RS NZP-CSI-RS-ResourceId, resourceMapping CSI-RS-ResourceMapping, absoluteFrequencyCSI-RS ARFCN-ValueNR, periodicityAndOffset CSI-ResourcePeriodicityAndOffset OPTIONAL, qcl-Info TCI-StateId OPTIONAL, ra-OccasionList SEQUENCE(SIZE(1..maxRAOccasionsPerCSIRS)) OFINTEGER(0..maxRAOccasions−1) OPTIONAL, -- Need R ra-PreambleIndex INTEGER(0..63) OPTIONAL, -- Need R  ... }-- TAG-VAR-BEAM-FAILURE-RECOVERY-CONFIG-STOP -- ASN1STOP

An example RRC IE and procedure that could be used if an RRCReconfiguration message carries a beam FailureRecoveryConfig object areshown below, and cause a UE to copy content to a variablevarBeamFailureRecoveryConfig. See in particular the element in bold andunderline.

  -- ASN1START -- TAG-RRCRECONFIGURATION-STARTRRCReconfiguration-IEs: SEQUENCE { radioBearerConfig RadioBearerConfig OPTIONAL, -- Need M secondaryCellGroup OCTET STRING(CONTAINING CellGroupConfig)OPTIONAL, -- Need M  measConfig MeasConfig OPTIONAL, -- Need M beamFailureRecoveryConfig BeamFailureRecoveryConfig OPTIONAL, -- Need M lateNonCriticalExtension OCTET STRING OPTIONAL, nonCriticalExtension RRCReconfiguration-v1530-IEs }-- TAG-RRCRECONFIGURATION-STOP -- ASN1STOP

According to procedure in an embodiment, a UE shall:

-   -   1> for each bfr-CandidateIndex included in the received        bfr-DedicatedRSList:        -   2> if an entry with the matching bfr-CandidateIndex exists            in the bfr-DedicatedRSList within the            VarBeamFailureRecoveryConfig, for this entry:            -   3> reconfigure the entry with the value received for                this bfr-CandidateBeam;        -   2> else:            -   3> add a new entry for the received bfr-CandidateBeam to                the bfr-DedicatedRSList within                VarBeamFailureRecoveryConfig.

Some embodiments could involve introducing dedicated resources for BeamFailure Detection. This could be implemented in combination with orindependently from other features disclosed herein. In the examplebelow, text in bold and italic represents fields that could be deletedfrom current NR Release 15 configurations.

  -- ASN1START -- TAG-RADIOLINKMONITORINGCONFIG-STARTRadioLinkMonitoringConfig:= SEQUENCE { failureDetectionResourcesToAddModList SEQUENCE (SIZE(1..maxNrofFailureDetectionResources)) OF RadioLinkMonitoringRS OPTIONAL, --Need N  failureDetectionResourcesToReleaseList SEQUENCE (SIZE(1..maxNrofFailureDetectionResources)) OF RadioLinkMonitoringRS-Id OPTIONAL,-- Need N  

 

 

 

 

 

 

 ... } RadioLinkMonitoringRS::= SEQUENCE { radioLinkMonitoringRS-Id RadioLinkMonitoringRS-Id,

 

 detectionResource CHOICE { ssb-Index SSB-Index,csi-RS-Index NZP-CSI-RS-ResourceId  }  ... }-- TAG-RADIOLINKMONITORINGCONFIG-STOP -- ASN1STOP

The elements in bold and underline below illustrate an example ofintroducing UE variables maintaining a dedicated RS list for BeamFailure Detection.

-- ASN1START -- TAG-VAR=BEAM-FAILURE-DETECTION-CONFIG-STARTVarBeamFailureDetectionConfig::= SEQUENCE { bfd-DedicatedRSList SEQUENCE (SIZE(1..maxNrofBeamFailureDetectionResources)) OF BFD-DedicatedResourceOPTIONAL } BFD-DedicatedResource::= SEQUENCE { bfd-RS-Index INTEGER (1..maxNrofBeamFailureDetectionResources), bfd-Resource BFD-Resource, } BFD-Resource::= CHOICE { ssb BFD-SSB-Resource,  csi-RS BFD-CSI-RS-ResourceId }BFD-SSB-Resource::= SEQUENCE {  ssb-Index SSB-Index, physCellId PhysCellId,  ssbFrequency ARFCN-ValueNR,  ... }-- TAG-VAR-BEAM-FAILURE-DETECTION-CONFIG-STOP -- ASN1STOP

SSB/NZP CSI-RS resource definition for BFD, for example, could includesuch information as time/frequency location and QCL assumptions, asillustrated by the elements highlighted in bold and underline below.

  -- ASN1START -- TAG-VAR=BEAM-FAILURE-DETECTION-CONFIG-STARTBFD-SSB-Resource::=   SEQUENCE {  ssb   SSB-Index,  ssbFrequency  ARFCN-ValueNR,  ra-PreambleIndex   INTEGER (0..63),  ... }BFD-CSIRS-Resource ::=   SEQUENCE {  csi-RS  NZP-CSI-RS-ResourceId, resourceMapping   CSI-RS-ResourceMapping,  absoluteFrequencyCSI-RS   ARFCN-ValueNR,  periodicityAndOffset  CSI-ResourcePeriodicityAndOffset OPTIONAL,  qcl-Info TCI-StateId,   OPTIONAL,  ra-OccasionList  SEQUENCE (SIZE(1..maxRA-OccasionsPerCSIRS)) OFINTEGER (0..maxRA-Occasions−1)    OPTIONAL, -- Need R  ra-PreambleIndex INTEGER (0..63) OPTIONAL, -- Need R  ... }-- TAG-VAR-BEAM-FAILURE-DETECTION-CONFIG-STOP -- ASN1STOP

An example RRC IE and procedure that could be used if an RRC

Reconfiguration message carries a beam FailureDetectionConfig object areshown below, and cause a UE to copy content to a variablevarBeamFailureRecoveryConfig. See in particular the element in bold andunderline.

  -- ASN1START -- TAG-RRCRECONFIGURATION-STARTRRCReconfiguration-IEs: SEQUENCE { radioBearerConfig RadioBearerConfig OPTIONAL, -- Need M secondaryCellGroup OCTET STRING(CONTAINING CellGroupConfig)OPTIONAL, -- Need M  measConfig MeasConfig OPTIONAL, -- Need M beamFailureDetectionConfig BeamFailureDetectionConfig OPTIONAL, --Need N  lateNonCriticalExtension OCTET STRING OPTIONAL, nonCriticalExtension RRCReconfiguration-v1530-IEs }-- TAG-RRCRECONFIGURATION-STOP -- ASN1STOP

According to procedure, in an embodiment a UE shall:

-   -   1> for each bfd-RSIndex included in the received        bfd-DedicatedRSList:        -   2> if an entry with the matching bfd-RS Index exists in the            bfd-DedicatedRSList within the            VarBeamFailureDetectionConfig, for this entry:            -   3> reconfigure the entry with the value received for                this bfd-Resource;        -   2> else:            -   3> add a new entry for the received bfd-Resource to the                bfd-DedicatedRSList within                VarBeamFailureDetectionConfig.

The detailed examples provided above are intended solely forillustrative purposes. Embodiments could include subsets of one or moredisclosed features, implemented as shown and/or described in one or moreexamples or in different ways that are still consistent with the presentdisclosure.

For example, a UE in accordance with the teachings herein could beconsidered as having a new memory or configuration module, the purposeof which is to maintain a record such as a list of communicationresources for beam management and a record such as a list of QCLassumptions linking reference signals together. Network equipment suchas a gNB could configure communication resources for beam management atthe UE using higher-layer signaling such as RRC signaling. Those beammanagement resources could belong to one or more cells, each cellcorresponding to a given gNB for example. In an embodiment, eachresource could correspond to a given beam transmitted by a given gNB.QCL assumptions link reference signals together, and linkage could beestablished by configuring a QCL information object in a given physicalchannel (e.g. PDCCH, PDSCH). After a QCL information object isconfigured, it links the reference signals sent by a given physicalchannel to a reference signal defined in the UE's beam managementmodule.

The UE could perform functions of beam management such as Beam FailureDetection (BFD) and/or Beam Failure Recovery (BFR) based on thecommunication resources configured in the BM module. The UE couldmaintain dedicated BFD and BFR modules configured by network equipmentvia higher-layer signaling. The BFD and BFR modules refer to resourcesdefined in the beam management module (e.g., through identifiers ofresources) in some embodiments.

Network equipment could inform the UE about the QCL assumptions to usefor demodulating PDCCH and PDSCH DMRSs transmitted as part of PDCCH andPDSCH channels at any given time, using semi-static (MAC-CE) or dynamic(DCI) commands. These commands link the reference signals sent as partof the channel with a reference signal defined in the UE's beammanagement module. Reference signals defined in the UE's beam managementmodule could belong to one or more cells or gNBs, thereby enablingmobility between cells. Detailed examples of RRC signaling for the beammanagement module, beam management resource list and QCL assumption listare provided above.

A UE beam management module could thus define and/or managecommunication resources for beam management as well as corresponding QCLassumptions that the UE can make regarding reference signals sent aspart of a physical channel. The beam management module is separate from(e.g., stored separately from, located outside of, or otherwiseimplemented externally from) a module that is used to hold thecell-specific configuration such as serving cell configuration.Technical advantages of such a solution could include, for example, anyone or more of the following:

-   -   enabling beam management to be carried out between cells,        including beam switching (e.g., QCL assumption update), Beam        Failure Detection and/or Beam Failure Recovery;    -   reducing data connectivity interruption due to mobility, by        reducing the amount of higher-layer signaling exchange between        the UE and the network and thus reducing delay associated with        reception of such higher-layer signaling;        -   functions such as L3 filtering, cell-level filtering, and/or            beam selection can be performed at the network side, on L1            measurements sent by the UE, and commands for beam switching            in accordance with the measurements sent by the UE can be            sent to the UE by network equipment.

Communication resources defined in the beam management module correspondto different beams, which could belong to different gNBs. Thoseresources are configured upon the UE completing initial access andcorrespond to one or more gNBs. Unlike in LTE or NR Release 15, the UEdoes not need to be reconfigured every time it performs a handover,because information about communication resources used by different gNBsis already available at the UE. The only difference between a source andtarget cell from the physical layer's perspective is the referencesignal being used to demodulate the signals from the PDCCH/PDSCH.

Network equipment could instruct the UE as to which reference signalsare the ones to use for PDCCH and PDSCH reception. If a UE is at theedge between two cells, network equipment could instruct the UE toswitch to beams used by a target cell without breaking data connectivityor sending a higher-layer signaling message to initiate a handover. Suchbreaking of data connectivity or sending a higher-layer signalingmessage can lead to interruption in the UE's connectivity.

As noted above, L3 filtering on L1 measurements sent by the UE could beperformed at the network side, thus potentially simplifying the UEbehavior by treating inter-cell mobility the same way as it treats beammanagement.

Either or both of beam management and QCL assumption management coulddistinguish embodiments over NR Release 15 solutions that are referencedherein. For example, in some embodiments a UE has a module to maintain arecord such as a list of resources for beam management. As noted above,communication resources for beam management at the UE could beconfigured by network equipment using higher-layer signaling such as RRCsignaling. The beam management resources could belong to one or moregNBs, with each gNB corresponding to a different cell for example. Insome embodiments, each resource corresponds to a given beam transmittedor received by a given gNB.

A UE could perform functions of beam management such as Beam FailureDetection and/or Beam Failure Recovery based on the resources configuredin the beam management module. The UE could maintain dedicated BFD andBFR modules configured by network equipment via higher-layer signaling.The BFD and BFR modules refer to communication resources defined in thebeam management module (e.g., through identifiers of resources).

In some embodiments, the UE has a module that defines resources for beammanagement, and the beam management module is located outside of amodule that is used to hold cell-specific configuration such as servingcell configuration. Technical advantages could include either or both ofthe following:

-   -   enabling beam management to be carried out between cells;    -   functions such as L3 filtering, cell-level filtering, and beam        selection on L1 measurements sent by the UE could be performed        at a network side, and network equipment could send commands for        beam switching in accordance with the measurements sent by the        UE.

Communication resources defined in the beam management module correspondto different beams, which could belong to different gNBs. As a result,the UE does not need to be reconfigured every time it performs ahandover, because information about communication resources used bydifferent gNBs is already available at the UE.

As noted above, L3 filtering on L1 measurements sent by the UE could beperformed at the network side, thus potentially simplifying the UEbehavior by treating inter-cell mobility the same way as it treats beammanagement.

In an embodiment, the UE has a new module whose purpose is to maintain alist of QCL assumptions linking reference signals together. Networkequipment configures those QCL assumptions at the UE using higher-layersignaling (i.e. RRC). Those QCL assumptions may correspond to one ormore gNBs, with each gNB corresponding to a different cell in someembodiments. QCL assumptions link reference signals together, and thelinkage is established by configuring a QCL information object in agiven physical channel (e.g. PDCCH, PDSCH) in some embodiments.

QCL assumption management could also or instead distinguish disclosedembodiments over NR Release 15 solutions that are referenced herein. Insome embodiments, the UE has a module to maintain a record such as alist of QCL assumptions linking reference signals together. Networkequipment configures those QCL assumptions at the UE using higher-layersignaling such as RRC signaling. Those QCL assumptions may correspond toone or more gNBs, with each gNB corresponding to a different cell insome embodiments. QCL assumptions link reference signals together, andthe linkage is established by configuring a QCL information object in agiven physical channel (e.g. PDCCH, PDSCH) in some embodiments.

Network equipment could inform a UE about QCL assumptions to use fordemodulating PDCCH and PDSCH channels at any time, using semi-static ordynamic commands (MAC-CE and DCI respectively). These commands link thereference signals sent as part of the channel with a reference signaldefined in the UE's beam management module. Reference signals defined inthe UE's beam management module could belong to one or more gNBs, thusenabling UE mobility between cells.

In some embodiments, a UE has a beam management module that defines QCLassumptions for one or more gNBs, and the beam management module islocated outside of a module used to hold cell-specific configurationsuch as serving cell configuration. Technical advantages of such asolution could include either or both of the following:

-   -   enabling beam management to be carried out between cells;    -   reducing data connectivity interruption due to mobility, by        reducing the amount of higher-layer signaling exchange between        the UE and network equipment and thus reducing delay associated        with reception of such higher-layer signaling.

Network equipment could instruct the UE as to which reference signalsare the ones to use for PDCCH and PDSCH reception. If a UE is at theedge between two cells, network equipment could instruct the UE toswitch to beams used by a target cell without breaking data connectivityor sending a higher-layer signaling message to initiate a handover.

These and other features are illustrated in FIGS. 11-13 .

FIG. 11 is a flow diagram illustrating a method according to anotherembodiment. The example method 1100 involves sending at operation 1102,by network equipment, a higher-layer configuration message containing abeam management module or configuration, in this example CSI-RSresources. At operation 1104, FIG. 11 illustrates a UE performing beammanagement based on the resources in the received beam managementmodule, which is an example of a higher-layer configuration referencedherein. At operation 1106 the UE performs channel measurements andreports to the network equipment, and at 1108 the network equipmentperforms beam consolidation/selection and optionally L3 filtering basedon the UE's L1 measurement reports.

FIG. 11 could include other operations as well, such as determining, bythe network equipment, whether the UE is to transition to a differentbeam and sending, by the network equipment to the UE, a beam switchingcommand or indication responsive to determining that the UE is totransition to a different beam.

FIG. 12 is a flow diagram illustrating a method according to a furtherembodiment. In the example method 1200, network equipment sends ahigher-layer configuration message containing a beam management moduleor configuration, in this example QCL assumptions. At operation 1204,FIG. 12 illustrates the network equipment sending a semi-static/dynamiccommand activating QCL assumptions for channels, shown as PDCCH/PDSCH.Such a command could be sent to a UE for initial activation, and/orafter determining that the UE is to transition to a different beam. FIG.12 also illustrates, at operation 1206, the UE applying the activatedQCL assumptions for reception of PDCCH/PDSCH transmissions. Similarfeatures could also or instead be provided for UL transmissions.

Embodiments have been disclosed by way of example herein primarily inthe context of methods. Apparatus or system implementations are alsocontemplated. FIG. 13 , for example, is a block diagram illustratingfeatures that could be implemented in a communication system 1300 at aUE and network equipment.

As shown, a UE could be configured by network equipment to monitorcommunication resources such as a number K of beams associated with eachof a number N of gNBs. Each subset of beams associated with a gNBincludes the same number of beams in the example shown, but in otherembodiments different gNBs could have different numbers of beams.

The UE performs channel measurements and could report raw measurementsor, as shown, filtered measurements based on L1 filtering at operation1302. Channel measurement reporting is shown in FIG. 13 as L1-based beamreporting at operation 1304.

At the network side, L3-based beam filtering of measurement reportscould be applied at operation 1312, or beam consolidation 1314 andL3-based cell filtering 1316 could be applied. As described herein, insome embodiments these functions could be performed at the network siderather than the UE side.

FIGS. 14 and 15 illustrate example devices that may implement themethods and teachings according to this disclosure, in more detail thanFIG. 13 . In particular, FIG. 14 illustrates an example ED 1410, andFIG. 15 illustrates an example base station 1520. These components couldbe used in the system 100 (FIG. 1 ) or in any other suitable system.

As shown in FIG. 14 , the ED 1410 includes at least one processing unit1400. The processing unit 1400 implements various processing operationsof the ED 1410. For example, the processing unit 1400 could performsignal coding, data processing, power control, input/output processing,or any other functionality enabling the ED 1410 to operate in acommunication system. The processing unit 1400 may also be configured toimplement some or all of the functionality and/or embodiments describedin more detail above. Each processing unit 1400 includes any suitableprocessing or computing device configured to perform one or moreoperations. Each processing unit 1400 could, for example, include amicroprocessor, microcontroller, digital signal processor, fieldprogrammable gate array, or application specific integrated circuit.

The ED 1410 also includes at least one transceiver 1402. The transceiver1402 is configured to modulate data or other content for transmission byat least one antenna or NIC (Network Interface Controller) 1404. Thetransceiver 1402 is also configured to demodulate data or other contentreceived by the at least one antenna 1404. Each transceiver 1402includes any suitable structure for generating signals for wirelesstransmission and/or processing signals received wirelessly or by wire.Each antenna 1404 includes any suitable structure for transmittingand/or receiving wireless signals. One or multiple transceivers 1402could be used in the ED 1410, and one or multiple antennas 1404 could beused in the ED 1410. Although shown as a single functional unit, atransceiver 1402 could be implemented using at least one transmitter andat least one separate receiver.

The ED 1410 further includes one or more input/output devices 1406 orinterfaces. The input/output devices 1406 facilitate interaction with auser or other devices (network communications) in the network. Eachinput/output device 1406 includes any suitable structure for providinginformation to or receiving/providing information from a user, such as aspeaker, microphone, keypad, keyboard, display, or touch screen,including network interface communications.

In addition, the ED 1410 includes at least one memory 1408. The memory1408 stores instructions and data used, generated, or collected by theED 1410. For example, the memory 1408 could store software instructionsor modules configured to implement some or all of the functionalityand/or embodiments described above and that are executed by theprocessing unit(s) 1400. Each memory 1408 includes any suitable volatileand/or non-volatile storage and retrieval device(s). Any suitable typeof memory may be used, such as random access memory (RAM), read onlymemory (ROM), hard disk, optical disc, subscriber identity module (SIM)card, memory stick, secure digital (SD) memory card, and the like.

As shown in FIG. 15 , the base station 1520 includes at least oneprocessing unit 1500, at least one transmitter 1502, at least onereceiver 1504, one or more antennas 1506, at least one memory 1508, andone or more input/output devices or interfaces 1516. A transceiver, notshown, may be used instead of the transmitter 1502 and receiver 1504. Ascheduler 1503 may be coupled to the processing unit 1500. The scheduler1503 may be included within or operated separately from the base station1520. The processing unit 1500 implements various processing operationsof the base station 1520, such as signal coding, data processing, powercontrol, input/output processing, or any other functionality. Theprocessing unit 1500 can also be configured to implement some or all ofthe functionality and/or embodiments described in more detail above.Each processing unit 1500 includes any suitable processing or computingdevice configured to perform one or more operations. Each processingunit 1500 could, for example, include a microprocessor, microcontroller,digital signal processor, field programmable gate array, or applicationspecific integrated circuit.

Each transmitter 1502 includes any suitable structure for generatingsignals for wireless transmission to one or more EDs or other devices.Each receiver 1504 includes any suitable structure for processingsignals received wirelessly or by wire from one or more EDs or otherdevices. Although shown as separate components, at least one transmitter1502 and at least one receiver 1504 could be combined into atransceiver. Each antenna 1506 includes any suitable structure fortransmitting and/or receiving wireless signals. While a common antenna1506 is shown here as being coupled to both the transmitter 1502 and thereceiver 1504, one or more antennas 1506 could be coupled to thetransmitter(s) 1502, and one or more separate antennas 1506 could becoupled to the receiver(s) 1504. Each memory 1508 includes any suitablevolatile and/or non-volatile storage and retrieval device(s) such asthose described above in connection to the ED 1410. The memory 1508stores instructions and data used, generated, or collected by the basestation 1520. For example, the memory 1508 could store softwareinstructions or modules configured to implement some or all of thefunctionality and/or embodiments described herein and that are executedby the processing unit(s) 1500.

Each input/output device 1516 facilitates interaction with a user orother devices (network communications) in the network. Each input/outputdevice 1516 includes any suitable structure for providing information toor receiving/providing information from a user, including networkinterface communications.

It should be appreciated that one or more steps of the embodimentmethods provided herein may be performed by corresponding units ormodules. For example, a signal may be transmitted by a transmitting unitor a transmitting module. A signal may be received by a receiving unitor a receiving module. A signal may be processed by a processing unit ora processing module. Other steps may be performed by these and/or othermodules. The respective units/modules may be implemented using hardware,components that execute software, or a combination thereof. Forinstance, one or more of the units/modules may be or include one or moreintegrated circuits, such as field programmable gate arrays (FPGAs) orapplication-specific integrated circuits (ASICs). It will be appreciatedthat where the modules are implemented using software, they may beretrieved by a processor, in whole or part as needed, individually ortogether for processing, in single or multiple instances, and that themodules themselves may include instructions for further deployment andinstantiation.

In general, hardware, firmware, components which execute software, orsome combination thereof could be used in implementing featuresdisclosed herein. Electronic devices that might be suitable forimplementing any or all of these components include, among others,microprocessors, microcontrollers, Programmable Logic Devices (PLDs),Field Programmable Gate Arrays (FPGAs), Application Specific IntegratedCircuits (ASICs), and other types of “intelligent” integrated circuits.

Any of various types of memory devices could be implemented. The memory1408 and/or the memory 1508, for example, could include one or morephysical memory devices. Solid-state memory devices such as a Flashmemory device, and/or memory devices with movable or even removablestorage media, could be implemented.

FIG. 14 and FIG. 15 illustrate examples of a UE and network equipment,respectively, in which embodiments could be implemented. More generally,an apparatus such as a UE could include a processor and a non-transitorycomputer readable storage medium, such as the processing unit 1400 andmemory 1408 in FIG. 14 . In such an embodiment, the storage mediumstores programming for execution by the processor, and the programmingcould include instructions to receive, by the UE from a first basestation, an indication signal for indicating to the UE a communicationresource for a second reference signal from a higher-layer configurationfrom the first base station to the UE. The communication resource forthe second reference signal is associated with a second base station,and is part of the higher-layer configuration. The indication signalcould be received, for example, through a receiver or a transceiver suchas the transceiver 1402 in FIG. 14 . The higher-layer configurationincludes a communication resource for a first reference signalassociated with the first base station, and also includes thecommunication resource for the second reference signal associated withthe second base station.

The programming could include instructions to communicate, by the UEwith the second base station, a data transmission or a control signaltransmission using a respective data channel or control channelassociated with the communication resource for the second referencesignal. Such communication could be through a transmitter ortransceiver, for example, such as the transceiver 1402 in FIG. 14 .

Embodiments could include other features, such as any one or more of thefollowing, in any of various combinations:

-   -   the programming further includes instructions to receive, by UE,        the higher-layer configuration from the first base station;    -   the indication signal is or includes QCL information;    -   the indication signal is or includes a MAC-CE indication of the        communication resource for the second reference signal;    -   the indication signal is or includes a DCI indication of the        communication resource for the second reference signal;    -   the indication signal is or includes an RRC indication of the        communication resource for the second reference signal;    -   the programming further includes instructions to perform, by the        UE, channel measurements for a channel used for communicating a        data transmission or a control signal transmission with the        first base station;    -   the programming further includes instructions to communicate, by        the UE to the first base station, an indication of the channel        measurements;    -   the higher-layer configuration further includes a communication        resource for beam failure recovery.

Other features that could be implemented in UE embodiments could be orbecome apparent, for example, from the method embodiments disclosedherein.

A base station, which is illustrative of network equipment, couldinclude a processor and a non-transitory computer readable storagemedium, such as the processing unit 1500 and memory 1508 in FIG. 15 . Insuch an embodiment, the storage medium stores programming for executionby the processor, and the programming could include instructions togenerate, by the base station, an indication signal for indicating to aUE a communication resource for a second reference signal from ahigher-layer configuration from the base station. The communicationresource for the second reference signal is associated with a secondbase station, and is part of the higher-layer configuration. Thehigher-layer configuration includes a communication resource for a firstreference signal associated with the first base station, and alsoincludes the communication resource for the second reference signalassociated with the second base station.

The programming could include instructions to transmit the indicationsignal from the base station to the UE, to enable the UE to communicatewith the second base station, a data transmission or a control signaltransmission using a respective data channel or control channelassociated with the communication resource for the second referencesignal. The indication signal could be transmitted, for example, througha transceiver or a transmitter such as the transmitter 1502 in FIG. 15 .

Network equipment embodiments could include other features, such as anyone or more of the following, in any of various combinations:

-   -   the programming further includes instructions to transmit, by        the base station, the higher-layer configuration to the UE;    -   the indication signal is or includes QCL information;    -   the indication signal is or includes a MAC-CE indication of the        communication resource for the second reference signal;    -   the indication signal is or includes a DCI indication of the        communication resource for the second reference signal;    -   the indication signal is or includes an RRC indication of the        communication resource for the second reference signal;    -   the programming further includes instructions to receive, by the        base station from the UE, an indication of channel measurements        performed by the UE for a channel used for communicating a data        transmission or a control signal transmission with the base        station;    -   the higher-layer configuration further includes a communication        resource for beam failure recovery.

Other features that could be implemented in network equipmentembodiments could be or become apparent, for example, from the methodembodiments disclosed herein.

Whereas beam management features are limited to intra-cell in NR Release15 and inter-cell beam management is treated as a mobility problem(i.e., when a UE changes cells it is reconfigured via higher-layersignaling), in accordance with aspects of the present disclosure beammanagement features are extended to inter-cell mobility between cells.Some embodiments enable inter-cell beam management, for example bymanaging QCL assumptions independently from serving cell configurations.

In some embodiments, QCL assumptions are maintained for different beamscorresponding to different gNBs to enable beam switching between cells.Physical layer control/data channels could be semi-statically ordynamically signaled about which QCL assumptions are to be used for beammanagement for intra-cell and inter-cell scenarios.

Embodiments could enable mobility without RRC involvement across cells,for example by defining resources for beam management (e.g., beamfailure detection, beam failure recovery) independently from servingcell configurations.

UE-centric beam management could be provided in some embodiments. Forexample, beam management resource configuration could be managedindependently of cells, and in some embodiments is customizable for eachUE.

In some embodiments, the RRC reconfiguration IE carries a BeamManagement IE with the definition of Beam Management resources andresource sets. In another embodiment, network equipment configuresresource sets for Beam Management and configures resources to the UEwhich may be used for different purposes (e.g. channel estimation, beammanagement, channel state information). Each BM resource set containsone or more resources (e.g. SS/PBCH block or NZP-CSI-RS). Each resourceset may correspond to a TRP set that belongs to a source cell or aneighbor cell. The one or more resources configured for each BM resourceset are defined in another RRC IE, e.g. a UE internal variable or an IEdefined inside a cell group configuration IE.

The BM resource set may contain parameters used by the UE for thepurpose of beam measurement and/or deriving beam measurement results. Anexample of a UE procedure for resource sets defined using NZP CSI-RSresources is as follows:

If the UE is configured to derive RSRP, RSRQ and SINR measurementresults for BM resource sets configured in thebeamManagementCsirsResourceSetToAddModList parameter, then the UE shall:

-   -   1> For each beam set measurement quantity to be derived based on        CSI-RS:        -   2> if NrofCsirsToAverage in the BM resource set is not            configured; or        -   2> if absThresholdCSI-RS in the BM resource set is not            configured; or        -   2> if the highest beam measurement quantity value is below            or equal to absThresholdCSI-RS:            -   3> derive each beam measurement quantity based on the BM                resource with the highest beam measurement quantity                value;        -   2> else:            -   3> derive each beam set measurement quantity based on                CSI-RS as the linear power scale average of the highest                beam measurement quantity values above                absThresholdCSI-RS where the total number of averaged                beams shall not exceed NrofCsirsToAverage.

Network equipment can take advantage of configuring BM resource sets tothe UE and the network equipment can keep a record of correspondencebetween cells/TRPs and BM resource sets. This is one way of achieving“cell-transparent”, “UE-centric” or “UE-specific” Beam Management.

If a UE is configured with a BM resource set containing one or more NZPCSI-RS resources without any parameter providing a timing reference fordemodulating those resources, then the UE may assume that the sourcecell's timing reference applies to the NZP CSI-RS resources in that BMresource set.

In some embodiments, network equipment uses MAC-CE commands in order toindicate which TCI states are to be used by the UE for demodulatingPDCCH or PDSCH DMRSs. TCI states correspond to individual BM resources(e.g. SS/PBCH block, NZP CSI-RS) and for each resource a given QCLassumption type is configured (e.g. delay spread, average delay, Dopplerspread, Doppler shift, Spatial Rx filter). In another embodiment,network equipment uses TCI states corresponding to BM resource sets anda given QCL assumption type is configured. The BM resources contained inthe BM resource set all apply the QCL assumption given in the TCI state.An example of the TCI-State and QCL-Info IEs is given below:

  -- ASN1START -- TAG-TCI-STATE-START TCI-State::= SEQUENCE { tci-StateId TCI-StateId,  qcl-Type1 QCL-Info, qcl-Type2 QCL-Info OPTIONAL, -- Need R } QCL-Info::= SEQUENCE { referenceSignalSet CHOICE { csi-rs NZP-CSI-RS-ResourceSetId,ssb CSI-SSB-ResourceSetId  } qcl-Type ENUMERATED {typeA, typeB, typeC, typeD},  ... }-- TAG-TCI-STATE-STOP -- ASN1STOP

In an embodiment, network equipment sends a MAC-CE command with TCIstate indications that could be similar to those in previous embodimentsdescribed above. One difference in the present embodiment could be thatthe TCI state with the matching TCI-StateId will indicate a set ofresources as opposed to individual resource.

One example of UE behaviour in response to receiving a TCI indicationfrom the network indicating a BM resource set and a QCL assumption touse for resources in that BM resource set, is to monitor all theresources that belong to the indicated BM resource set and apply the QCLassumptions it derived for each resource in the BM resource set towardsthe demodulation of the PDCCH/PDSCH DMRSs.

Another example of UE behaviour in response to receiving a TCIindication from the network indicating a BM resource set and a QCLassumption to use for resources in that BM resource set, is to monitorall the resources that belong to the indicated BM resource set usingsome priority rule.

As an example: the UE could use a priority rule based on the periodicityof the resource (e.g. SS/PBCH block or NZP CSI-RS), such that a UE usesQCL assumptions from aperiodic resources with the highest priority,followed by semi-persistent resources and finally by periodic resources.If the indicated BM resource set contains at least one aperiodicresource, then the UE uses the QCL assumptions from the at least oneaperiodic resources to demodulate PDCCH/PDSCH DMRSs. If the indicated BMresource set does not contain aperiodic resources and contains at leastone semi-persistent resource, then the UE uses the QCL assumptions fromthe at least one semi-persistent resources to demodulate PDCCH/PDSCHDMRSs. If the indicated BM resource set does not contain aperiodicresources and does not contain semi-persistent resources and contains atleast one periodic resource, then the UE uses the QCL assumptions fromthe at least one periodic resources to demodulate PDCCH/PDSCH DMRSs.

An example of the NZP CSI-RS resource IE is given below:

  -- ASN1START -- TAG-NZP-CSI-RS-RESOURCE-STARTNZP-CSI-RS-Resource::= SEQUENCE { nzp-CSI-RS-ResourceId NZP-CSI-RS-ResourceId, resourceMapping CSI-RS-ResourceMapping, powerControlOffset INTEGER (−8..15), powerControlOffsetSS ENUMERATED {db−3, db0, db3, db6} OPTIONAL, -- NeedR  scramblingID ScramblingId, resourceType ENUMERATED{aperiodic, semiPersistent, periodic}, periodicityAndOffset CSI-ResourcePeriodicityAndOffset OPTIONAL, -- CondPeriodicOrSemiPersistent  ... } -- TAG-NZP-CSI-RS-RESOURCE-STOP-- ASN1STOP

NZP CSI-RS resource configuration could include a parameter indicatingthe type of the resource, i.e. whether it is an aperiodic,semi-persistent or periodic NZP CSI-RS resource. Based on the aboveexample, if an NZP CSI-RS resource is configured with resource Typefield set to aperiodic, then it is an aperiodic NZP CSI-RS. A BMresource set may contain one or more of aperiodic, semi-persistent orperiodic resources, and therefore a BM resource could carry or includeresources of different type of periodicity.

In some embodiments, the RRC reconfiguration IE carries a Beam FailureRecovery IE with the definition of candidate beams corresponding tosource and neighbour cells. In another embodiment, network equipmentconfigures the UE with a control resource set (CORESET) for the purposeof Beam Failure Recovery.

A UE could be configured with a CORESET for Beam Failure Recoverythrough higher-layer configuration. The RRC IE holding the BFR CORESETin UE memory is stored outside of IEs used for storing serving cellconfigurations. A UE monitors PDCCH candidates in one or more searchspaces located on the BFR CORESET. The network deployment is done insuch a way that the source and neighbor cells a UE monitors signals usethe same BFR CORESET.

In an embodiment, a UE maintains candidate beams as part of the BFR IE.After the UE detects a certain number of beam failure instances, the UEstarts by scanning through the candidate beams configured in the BFR IE.The UE selects the first candidate beam whose signal quality is above athreshold defined in the BFR IE. Once the UE has found such a candidatebeam, the UE starts the beam failure recovery request procedure. Anexample of the procedure followed by the UE in an embodiment is asfollows:

-   -   1> If a UE is configured with a Beam Failure Recovery IE and the        MAC entity of the UE transmitted a random access preamble for        beam failure recovery request:        -   2> the UE starts the random access response window as            configured in the Beam Failure Recovery IE;        -   2> the UE monitors for a PDCCH transmission scrambled by the            UE's C-RNTI on a search space located on the BFR CORESET            while the random access response window is still running.    -   1> Else:        -   2> the UE starts the random access response window as            configured in the Random Access IE;        -   2> the UE monitors for a PDCCH transmission scrambled by the            UE's RA-RNTI while the random access response window is            still running.

In another embodiment, network equipment configures the UE with an RNTIfor beam failure recovery purposes, or BFR-RNTI, in the BFR IE. A UE isconfigured with one or more CORESET through higher-layer configuration.The BFR IE in UE memory is stored outside of IEs used for storingserving cell configurations. A UE monitors PDCCH candidates in one ormore search spaces located on the CORESET identified by CORESETId=0. Thenetwork deployment is done in such a way that the source and neighborcells share the pool of RNTIs for Beam Failure Recovery, and thereforesource and neighbor cells can communicate with the UE using theBFR-RNTI.

In an embodiment, a UE maintains candidate beams as part of the BFR IE.After the UE detects a certain number of beam failure instances, the UEstarts by scanning through the candidate beams configured in the BFR IE.The UE selects the first candidate beam whose signal quality is above athreshold defined in the BFR IE. Once the UE has found such a candidatebeam, the UE starts the beam failure recovery request procedure. Anexample of the procedure followed by the UE in an embodiment is asfollows:

-   -   1> If a UE is configured with a Beam Failure Recovery IE and the        MAC entity of the UE transmitted a random access preamble for        beam failure recovery request:        -   2> the UE starts the random access response window as            configured in the Beam Failure Recovery IE;        -   2> the UE monitors for a PDCCH transmission scrambled by the            UE's BFR-RNTI on a search space located on the CORESET            identified by CORESETId=0 while the random access response            window is still running.    -   1> Else:        -   2> the UE starts the random access response window as            configured in the Random Access IE;        -   2> the UE monitors for a PDCCH transmission scrambled by the            UE's RA-RNTI while the random access response window is            still running.

The UE monitors PDCCH candidates for DCI formats with CRC scrambled by aBFR-RNTI.

In another embodiment, network equipment configures the UE with a BFRCORESET and an RNTI for beam failure recovery purposes, or BFR-RNTI, inthe BFR IE.

A UE is configured with a CORESET for Beam Failure Recovery throughhigher-layer configuration. The RRC IE holding the BFR CORESET in UEmemory is stored outside of IEs used for storing serving cellconfigurations. A UE monitors PDCCH candidates in one or more searchspaces located on the BFR CORESET. The network deployment is done insuch a way that the source and neighbor cells a UE monitors signals fromuse the same BFR CORESET.

A UE maintains candidate beams as part of the BFR IE in someembodiments. After the UE detects a certain number of beam failureinstances, the UE starts by scanning through the candidate beamsconfigured in the BFR IE. The UE selects the first candidate beam whosesignal quality is above a threshold defined in the BFR IE. Once the UEhas found such a candidate beam, the UE starts the beam failure recoveryrequest procedure. An example of the procedure followed by the UE in anembodiment is as follows:

-   -   1> If a UE is configured with a Beam Failure Recovery IE and the        MAC entity of the UE transmitted a random access preamble for        beam failure recovery request:        -   2> the UE starts the random access response window as            configured in the Beam Failure Recovery IE;        -   2> the UE monitors for a PDCCH transmission scrambled by the            UE's BFR-RNTI on a search space located on the BFR CORESET            while the random access response window is still running.    -   1> Else:        -   2> the UE starts the random access response window as            configured in the Random Access IE;        -   2> the UE monitors for a PDCCH transmission scrambled by the            UE's RA-RNTI while the random access response window is            still running.

In some embodiments, the network configures the UE with resources (e.g.SS/PBCH blocks, NZP CSI-RS) for Beam Management, which may betransmitted from source or neighbor cells, and with TCI states thatassociate resources with QCL assumptions (e.g. delay spread, averagedelay, etc.). Network equipment could use MAC-CE commands to indicate tothe UE which reference signals use and what QCL assumptions to make inorder to demodulate PDCCH/PDSCH DMRSs. In another embodiment, the UEcould use the configuration of an active bandwidth part as a mechanismto implicitly indicate which BM resources the UE should monitor.

As a first example, if the UE is configured with an active downlinkbandwidth part (BWP) using higher-layer configuration and the UE isconfigured with BM resources (e.g. NZP CSI-RS) whose bandwidth iscontained within the bandwidth of the BWP and whose subcarrier spacingis the same as the subcarrier spacing used by the active DL BWP, thenthe UE could implicitly assume that it can monitor those BM resourcesand use QCL assumption type QCL-TypeD in order to demodulate PDCCH/PDSCHDMRSs.

As a second example, if the UE is configured with an active DL BWP usinghigher-layer configuration and the UE is configured with BM resourcesets and all the resources in the BM resource set are configured suchthat their bandwidth is contained with the bandwidth of the BWP andtheir subcarrier spacing is the same as that of the active DL BWP, thenthe UE could implicitly assume that it can monitor those BM resourcesand use QCL assumption type QCL-TypeD in order to demodulate PDCCH/PDSCHDMRSs.

As a third example, if the UE is configured with an active DL BWP usinghigher-layer configuration and the UE is configured with BM resourcesets and all the resources in the BM resource set are configured suchthat their bandwidth is contained with the bandwidth of the BWP andtheir subcarrier spacing is the same as that of the active DL BWP, ifthe BM resource sets contain at least one periodic resource then the UEcould implicitly assume that it can monitor those periodic BM resourcesand use QCL assumption type QCL-TypeD in order to demodulate PDCCH/PDSCHDMRSs.

For all three examples outlined above, the UE could equivalently use QCLassumptions QCL-TypeA, QCL-TypeB, QCL-TypeC or QCL-TypeD. The UE couldalso or instead equivalently implicitly assume that it can monitoraperiodic or semi-persistent BM resources. The UE could also or insteadreceive MAC-CE commands indicating TCI states to use jointly fordemodulating the PDCCH and the PDSCH DMRSs.

In some embodiments, network equipment configures the UE with resourcesfor Beam Management, Beam Failure Recovery and Beam Failure Detectionusing dedicated configurations. In another embodiment, network equipmentcould configure the UE with resources (e.g. SS/PBCH blocks, NZP CSI-RS)and set a parameter which specifies the purpose of the resource, e.g.any one or more of Beam Management, Beam Failure Recovery and BeamFailure Detection. An example of the NZP CSI-RS resource IE with such afield (“purpose”) is given below:

  -- ASN1START -- TAG-NZP-CSI-RS-RESOURCE-STARTNZP-CSI-RS-Resource::= SEQUENCE { nzp-CSI-RS-ResourceId NZP-CSI-RS-ResourceId, resourceMapping CSI-RS-ResourceMapping, powerControlOffset INTEGER (−8..15), powerControlOffsetSS ENUMERATED {db−3, db0, db3, db6} OPTIONAL, scramblingID ScramblingId, periodicityAndOffset CSI-ResourcePeriodicityAndOffset OPTIONAL, qcl-InfoPeriodicCSI-RS TCI-StateId OPTIONAL, purpose ENUMERATED {bm, bfr, bfd, bm-bfr, bm-bfd, bfr-bfd, bm-bfr-bfd}, ... } -- TAG-NZP-CSI-RS-RESOURCE-STOP -- ASN1STOP

In another embodiment, network equipment could configure the UE with BMNZP CSI-RS resources with an additional field indicating which SS/PBCHblock the UE can use as a timing reference point in order to determinethe timing reference for monitoring purposes. Equivalently, networkequipment could configure the UE with a BM resource set containing NZPCSI-RS resources and an additional field indicating which SS/PBCH blockthe UE can use as a timing reference point in order to determine thetiming reference for the resources defined in that BM resource set.

The present disclosure encompasses various embodiments, including theexamples below.

According to an example 1, a method involves receiving, by a UE from afirst base station, an indication signal for indicating to the UE acommunication resource of a second reference signal from a higher-layerUE configuration from the first base station, the higher-layerconfiguration further comprising a communication resource for a firstreference signal associated with the first base station and thecommunication resource for the second reference signal associated with asecond base station; communicating, by the UE with the second basestation, a data transmission or a control signal transmission using arespective data channel or control channel, the data channel or controlchannel associated with the communication resource of the secondreference signal.

An example 2 relates to the method of example 1, further comprising:receiving, by the UE, the higher-layer configuration from the first basestation.

An example 3 relates to the method of example 1 or example 2, whereinthe indication signal comprises a QCL assumption.

An example 4 relates to the method of any one of examples 1 to 3,wherein the indication signal comprises a MAC-CE indication of thecommunication resource of the second reference signal.

An example 5 relates to the method of any one of examples 1 to 3,wherein the indication signal comprises a DCI indication of thecommunication resource of the second reference signal.

An example 6 relates to the method of any one of examples 1 to 3,wherein the indication signal comprises an RRC indication of thecommunication resource of the second reference signal.

An example 7 relates to the method of any one of examples 1 to 6,further comprising: performing, by the UE, channel measurements for achannel used for communicating a data transmission or a control signaltransmission associated with the first base station; communicating, bythe UE to the first base station, an indication of the channelmeasurements.

An example 8 relates to the method of any one of examples 1 to 7,wherein the higher-layer configuration further comprises a communicationresource for beam failure recovery.

According to an example 9, a method involves: generating, by a firstbase station, an indication signal for indicating to a UE acommunication resource of a second reference signal from a higher-layerconfiguration from the first base station to the UE, the higher-layerconfiguration comprising a communication resource for a first referencesignal associated with the first base station and the communicationresource for the second reference signal associated with a second basestation; transmitting the indication signal from the first base stationto the UE, to enable the UE to communicate with the second base station,a data transmission or a control signal transmission using a respectivedata channel or control channel, the data channel or control channelassociated with the communication resource of the second referencesignal.

An example 10 relates to the method of example 9, further comprising:transmitting, by the first base station, the higher-layer configurationto the UE.

An example 11 relates to the method of example 9 or example 10, whereinthe indication signal comprises a QCL assumption.

An example 12 relates to the method of any one of examples 9 to 11,wherein the indication signal comprises a MAC-CE indication of thecommunication resource of the second reference signal.

An example 13 relates to the method of any one of examples 9 to 11,wherein the indication signal comprises a DCI indication of thecommunication resource of the second reference signal.

An example 14 relates to the method of any one of examples 9 to 11,wherein the indication signal comprises an RRC indication of thecommunication resource of the second reference signal.

An example 15 relates to the method of any one of examples 9 to 14,further comprising: receiving, by the first base station from the UE, anindication of channel measurements performed by the UE for a channelused for communicating a data transmission or a control signaltransmission with the first base station.

An example 16 relates to the method of any one of examples 9 to 15,wherein the higher-layer configuration further comprises a communicationresource for beam failure recovery.

According to an example 17, a UE comprises: a processor; and anon-transitory computer readable storage medium storing programming forexecution by the processor, the programming including instructions to:receive, by the UE from a first base station, an indication signal forindicating to the UE a communication resource of a second referencesignal from a higher-layer configuration from the first base station,the higher-layer configuration comprising a communication resource for afirst reference signal associated with the first base station and thecommunication resource for the second reference signal associated with asecond base station; communicate, by the UE with the second basestation, a data transmission or a control signal transmission using arespective data channel or control channel, the data channel or controlchannel associated with the communication resource of the secondreference signal.

An example 18 relates to the UE of example 17, wherein the programmingfurther includes instructions to: receive, by the UE, the higher-layerconfiguration from the first base station.

An example 19 relates to the UE of example 17 or example 18, wherein theindication signal comprises a QCL assumption.

An example 20 relates to the UE of any one of examples 17 to 19, whereinthe indication signal comprises a MAC-CE indication of the communicationresource of the second reference signal.

An example 21 relates to the UE of any one of examples 17 to 19, whereinthe indication signal comprises a DCI indication of the communicationresource of the second reference signal.

An example 22 relates to the UE of any one of examples 17 to 19, whereinthe indication signal comprises an RRC indication of the communicationresource of the second reference signal.

An example 23 relates to the UE of any one of examples 17 to 22, whereinthe programming further includes instructions to: perform, by the UE,channel measurements for a channel used for communicating a datatransmission or a control signal transmission with the first basestation; communicate, by the UE to the first base station, an indicationof the channel measurements.

An example 24 relates to the UE of any one of examples 17 to 23, whereinthe higher-layer configuration further comprises a communicationresource for beam failure recovery.

According to an example 25, a base station comprises: a processor; and anon-transitory computer readable storage medium storing programming forexecution by the processor, the programming including instructions to:generate, by the base station, an indication signal for indicating to aUE a communication resource of a second reference signal from ahigher-layer configuration from the base station to the UE, thehigher-layer configuration comprising a communication resource for afirst reference signal associated with the base station and thecommunication resource for the second reference signal associated with asecond base station; transmit the indication signal from the basestation to the UE, to enable the UE to communicate with the second basestation, a data transmission or a control signal transmission using arespective data channel or control channel, the data channel or controlchannel associated with the communication resource of the secondreference signal.

An example 26 relates to the base station of example 25, wherein theprogramming further includes instructions to: transmit, by the basestation, the higher-layer configuration to the UE.

An example 27 relates to the base station of example 25 or example 26,wherein the indication signal comprises a QCL assumption.

An example 28 relates to the base station of any one of examples 25 to27, wherein the indication signal comprises a MAC-CE indication of thecommunication resource of the second reference signal.

An example 29 relates to the base station of any one of examples 25 to27, wherein the indication signal comprises a DCI indication of thecommunication resource of the second reference signal.

An example 30 relates to the base station of any one of examples 25 to27, wherein the indication signal comprises an RRC indication of thecommunication resource of the second reference signal.

An example 31 relates to the base station of any one of examples 25 to30, wherein the programming further includes instructions to: receive,by the base station from the UE, an indication of channel measurementsperformed by the UE for a channel used for communicating a datatransmission or a control signal transmission with the base station.

An example 32 relates to the base station of any one of examples 25 to31, wherein the higher-layer configuration further comprises acommunication resource for beam failure recovery.

According to an example 33, a computer program product comprises anon-transitory computer readable storage medium storing programming, theprogramming including instructions to perform the method of any one ofexamples 1 to 8.

According to an example 34, a computer program product comprises anon-transitory computer readable storage medium storing programming, theprogramming including instructions to perform the method of any one ofexamples 9 to 16.

What has been described is merely illustrative of the application ofprinciples of embodiments of the present disclosure. Other arrangementsand methods can be implemented by those skilled in the art.

For example, although a combination of features is shown in theillustrated embodiments, not all of them need to be combined to realizethe benefits of various embodiments of this disclosure. In other words,a system or method designed according to an embodiment of thisdisclosure will not necessarily include all of the features shown in anyone of the Figures or all of the portions schematically shown in theFigures. Moreover, selected features of one example embodiment could becombined with selected features of other example embodiments.

While this disclosure has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of thedisclosure, will be apparent to persons skilled in the art uponreference to the description. It is therefore intended that the appendedclaims encompass any such modifications or embodiments.

Although the present disclosure has been described with reference tospecific features and embodiments thereof, various modifications andcombinations can be made thereto without departing from the disclosure.The description and drawings are, accordingly, to be regarded simply asan illustration of some embodiments of the disclosure as defined by theappended claims, and are contemplated to cover any and allmodifications, variations, combinations or equivalents that fall withinthe scope of the present disclosure. Therefore, although the presentdisclosure and its advantages have been described in detail, variouschanges, substitutions and alterations can be made herein withoutdeparting from the disclosure as defined by the appended claims.Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present disclosure, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present disclosure. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

In addition, although described primarily in the context of methods andapparatus, other implementations are also contemplated, as instructionsstored on a non-transitory computer-readable medium, for example. Suchmedia could store programming or instructions to perform any of variousmethods consistent with the present disclosure.

For example, a computer program product may comprise a non-transitorycomputer readable storage medium storing programming that includesinstructions to perform a method as disclosed herein.

As another example, a non-transitory computer readable storage mediummay store programming for execution by a processor, with the programmingincluding instructions to perform a method as disclosed herein. In anembodiment, the programming including instructions to: receive, by auser equipment (UE) from a first base station, an indication signal forindicating to the UE a communication resource for a second referencesignal associated with a second base station, wherein the communicationresource for the second reference signal is comprised in a higher-layerconfiguration from the first base station to the UE, and thehigher-layer configuration further comprises a communication resourcefor a first reference signal associated with the first base station; andcommunicate, by the UE with the second base station, a data transmissionor a control signal transmission using a respective data channel orcontrol channel, the data channel or control channel associated with thecommunication resource for the second reference signal.

Any of various features, such as any one or more of the following in anycombination, may be provided in computer program product and/ornon-transitory computer readable storage medium embodiments:

-   -   the programming further includes instructions to receive, by the        UE, the higher-layer configuration from the first base station;    -   the indication signal is or includes QCL information;    -   the indication signal is or includes a MAC-CE indication of the        communication resource for the second reference signal;    -   the indication signal is or includes a DCI indication of the        communication resource for the second reference signal;    -   the indication signal is or includes an RRC indication of the        communication resource for the second reference signal;    -   the programming further includes instructions to perform, by the        UE, channel measurements for a channel used for communicating a        data transmission or a control signal transmission with the        first base station;    -   the programming further includes instructions to communicate, by        the UE to the first base station, an indication of the channel        measurements;    -   the programming further includes instructions to perform, by the        UE, channel measurements for the data channel or control        channel;    -   the programming further includes instructions to communicate, by        the UE to the second base station, an indication of the channel        measurements for the data channel or the control channel;    -   the higher-layer configuration further comprises a communication        resource for beam failure recovery.

Moreover, any module, component, or device exemplified herein thatexecutes instructions may include or otherwise have access to anon-transitory computer/processor readable storage medium or media forstorage of information, such as computer/processor readableinstructions, data structures, program modules, and/or other data. Anon-exhaustive list of examples of non-transitory computer/processorreadable storage media includes magnetic cassettes, magnetic tape,magnetic disk storage or other magnetic storage devices, optical diskssuch as compact disc read-only memory (CD-ROM), digital video discs ordigital versatile disc (DVDs), Blu-ray Disc™, or other optical storage,volatile and non-volatile, removable and nonremovable media implementedin any method or technology, random-access memory (RAM), read-onlymemory (ROM), electrically erasable programmable read-only memory(EEPROM), flash memory or other memory technology. Any suchnon-transitory computer/processor storage media may be part of a deviceor accessible or connectable thereto. Any application or module hereindescribed may be implemented using computer/processorreadable/executable instructions that may be stored or otherwise held bysuch non-transitory computer/processor readable storage media.

1. A method comprising: receiving, by a user equipment (UE) from a firstbase station, a medium access control—control element (MAC-CE) commandindicating an active indication field for a TCI state for a referencesignal associated with a second base station; in response to the MAC-CEcommand, communicating, by the UE with the second base station, a datasignal transmission or a control signal transmission using a respectivedata channel or control channel, the data channel or control channelassociated with the TCI state for the reference signal, wherein the TCIstate comprises a QCL information with a Quasi-Colocation (QCL)assumption associated with the reference signal associated with thesecond base station, to use for communicating, by the UE with the secondbase station, the respective data channel or control channel.
 2. Themethod of claim 1, further comprising: receiving, by the UE, thehigher-layer configuration from the first base station.
 3. The method ofclaim 2, wherein the indication signal comprises a beam switchingcommand, the method further comprising: switching, by the UE, from afirst beam provided by the first base station to a second beam providedby the second base station in response to the indication signal.
 4. Themethod of claim 2, wherein the indication signal comprises a TCI Stateupdate message that references the communication resource for the secondreference signal.
 5. The method of claim 2, wherein the indicationsignal comprises a TCI State Activation message, the method furthercomprising: performing beam switching, by the UE, to switch from a firstbeam provided by the first base station to a second beam provided by thesecond base station in response to the indication signal.
 6. The methodof claim 2, wherein the indication signal comprises a beam indication,the method further comprising: performing beam switching in accordancewith the beam indication.
 7. The method of claim 1, further comprising:monitoring, by the UE, the resources in the beam management resource setand apply the QCL assumption for each resource in the beam managementresource set towards demodulation of the second reference signal.
 8. Themethod of claim 1, further comprising: monitoring, by the UE, theresources in the beam management resource set using a priority rule. 9.The method of claim 1, wherein the QCL information comprises a fieldassociated with the physical cell identity associated with the secondbase station.
 10. The method of claim 1, wherein the reference signal isa Synchronization Signal and Physical Broadcast Channel (SS/PBCH) blockor a non-zero power channel state information reference signal (NZPCSI-RS) associated with the second base station.
 11. An apparatus,comprising: a processor; and a non-transitory computer readable storagemedium storing programming for execution by the processor, theprogramming including instructions to: receive from a first basestation, a medium access control—control element (MAC-CE) commandindicating an active indication field for a TCI state for a referencesignal associated with a second base station; in response to the MAC-CEcommand, communicate with the second base station, a data signaltransmission or a control signal transmission using a respective datachannel or control channel, the data channel or control channelassociated with the TCI state for the reference signal, wherein the TCIstate comprises a QCL information with a Quasi-Colocation (QCL)assumption associated with the reference signal associated with thesecond base station, to use for communicating, by the UE with the secondbase station, the respective data channel or control channel.
 12. Theapparatus of claim 11, wherein the programming further includesinstructions to: receive the higher-layer configuration from the firstbase station.
 13. The apparatus of claim 12, wherein the indicationsignal comprises a beam switching command, wherein the programmingfurther includes instructions to: switch from a first beam provided bythe first base station to a second beam provided by the second basestation in response to the indication signal.
 14. The apparatus of claim12, wherein the indication signal comprises a TCI State update messagethat references the communication resource for the second referencesignal.
 15. The apparatus of claim 12, wherein the indication signalcomprises a TCI State Activation message, wherein the programmingfurther includes instructions to: perform beam switching to switch froma first beam provided by the first base station to a second beamprovided by the second base station in response to the indicationsignal.
 16. The apparatus of claim 12, wherein the indication signalcomprises a beam indication, wherein the programming further includesinstructions to: perform beam switching in accordance with the beamindication.
 17. A computer program product comprising a non-transitorycomputer readable storage medium storing programming, the programmingincluding instructions to: receive from a first base station, a mediumaccess control—control element (MAC-CE) command indicating an activeindication field for a TCI state for a reference signal associated witha second base station; in response to the MAC-CE command, communicatewith the second base station, a data signal transmission or a controlsignal transmission using a respective data channel or control channel,the data channel or control channel associated with the TCI state forthe reference signal, wherein the TCI state comprises a QCL informationwith a Quasi-Colocation (QCL) assumption associated with the referencesignal associated with the second base station, to use forcommunicating, by the UE with the second base station, the respectivedata channel or control channel.
 18. A non-transitory computer readablestorage medium storing programming for execution by a processor, theprogramming including instructions to: receive from a first basestation, a medium access control—control element (MAC-CE) commandindicating an active indication field for a TCI state for a referencesignal associated with a second base station; in response to the MAC-CEcommand, communicate with the second base station, a data signaltransmission or a control signal transmission using a respective datachannel or control channel, the data channel or control channelassociated with the TCI state for the reference signal, wherein the TCIstate comprises a QCL information with a Quasi-Colocation (QCL)assumption associated with the reference signal associated with thesecond base station, to use for communicating, by the UE with the secondbase station, the respective data channel or control channel.
 19. Thenon-transitory computer readable storage medium of claim 18, wherein theprogramming further includes instructions to: receive the higher-layerconfiguration from the first base station.
 20. The non-transitorycomputer readable storage medium of claim 18, wherein the programmingfurther includes instructions to: perform channel measurements for thedata channel or control channel; communicate to the second base station,an indication of the channel measurements for the data channel or thecontrol channel.